INFO: task kworker/u4:4:293 blocked for more than 143 seconds. Not tainted 5.5.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:4 D27240 293 2 0x80004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4081 schedule+0x188/0x210 kernel/sched/core.c:4155 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214 __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:1267 [inline] hashlimit_net_exit+0x40/0x210 net/netfilter/xt_hashlimit.c:1290 ops_exit_list net/core/net_namespace.c:172 [inline] cleanup_net+0x6f8/0xb80 net/core/net_namespace.c:597 process_one_work+0x7f5/0x10d0 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/u4:4/293: #0: ffff8880a9e85928 ((wq_completion)netns){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff8880a9e85928 ((wq_completion)netns){+.+.}, at: process_one_work+0x763/0x10d0 kernel/workqueue.c:2237 #1: ffffc90001db7d78 (net_cleanup_work){+.+.}, at: process_one_work+0x7a5/0x10d0 kernel/workqueue.c:2239 #2: ffffffff89355328 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa5/0xb80 net/core/net_namespace.c:559 #3: ffffffff89371970 (hashlimit_mutex){+.+.}, at: hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1267 [inline] #3: ffffffff89371970 (hashlimit_mutex){+.+.}, at: hashlimit_net_exit+0x40/0x210 net/netfilter/xt_hashlimit.c:1290 1 lock held by khungtaskd/1126: #0: ffffffff890d45c0 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 1 lock held by rsyslogd/8467: #0: ffff88809f24cb60 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x243/0x2e0 fs/file.c:801 2 locks held by getty/8557: #0: ffff888099285090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000179b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8558: #0: ffff888096896090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000182b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8559: #0: ffff8880a77c8090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8560: #0: ffff88809a362090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8561: #0: ffff88809263e090 (&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/8562: #0: ffff8880a2545090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000180b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8563: #0: ffff88808f8f0090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017632e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.4/9268: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1126 Comm: khungtaskd Not tainted 5.5.0-rc7-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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 9268 Comm: syz-executor.4 Not tainted 5.5.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline] RIP: 0010:hlock_class kernel/locking/lockdep.c:163 [inline] RIP: 0010:__lock_acquire+0xbb0/0x1bc0 kernel/locking/lockdep.c:3951 Code: 49 83 3e 00 0f 84 1b 07 00 00 48 8b 44 24 10 8a 04 38 84 c0 0f 85 e2 0b 00 00 48 8b 44 24 08 8b 18 81 e3 ff 1f 00 00 48 89 d8 <48> c1 e8 06 48 8d 3c c5 e0 88 e6 89 be 08 00 00 00 e8 9a 17 57 00 RSP: 0018:ffffc90005c2f900 EFLAGS: 00000002 RAX: 0000000000000a01 RBX: 0000000000000a01 RCX: ffffffff815b7550 RDX: 0000000000000000 RSI: 0000000000000008 RDI: dffffc0000000000 RBP: ffffc90005c2fa60 R08: dffffc0000000000 R09: fffffbfff13cd143 R10: fffffbfff13cd143 R11: 0000000000000000 R12: c280f7eaac1e6878 R13: ffff88809585a8d0 R14: ffffffff89ac18f0 R15: ffff88809585a040 FS: 00007f1130f37700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffc62a50c3c CR3: 000000008f876000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: 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 net/netfilter/xt_hashlimit.c:382 [inline] htable_destroy net/netfilter/xt_hashlimit.c:422 [inline] htable_put+0x2b8/0x620 net/netfilter/xt_hashlimit.c:449 hashlimit_mt_destroy_v2+0x5b/0x70 net/netfilter/xt_hashlimit.c:971 cleanup_match net/ipv4/netfilter/ip_tables.c:460 [inline] cleanup_entry+0x152/0x3b0 net/ipv4/netfilter/ip_tables.c:645 do_replace net/ipv4/netfilter/ip_tables.c:1148 [inline] do_ipt_set_ctl+0x3cc/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 tcp_setsockopt+0xbe/0xd0 net/ipv4/tcp.c:3158 sock_common_setsockopt+0x99/0xb0 net/core/sock.c:3149 __sys_setsockopt+0x582/0x720 net/socket.c:2117 __do_sys_setsockopt net/socket.c:2133 [inline] __se_sys_setsockopt net/socket.c:2130 [inline] __x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2130 do_syscall_64+0xf7/0x1c0 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:00007f1130f36c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f1130f376d4 RCX: 000000000045b349 RDX: 0000000000000040 RSI: 0002000000000000 RDI: 0000000000000003 RBP: 000000000075bfc8 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000020000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000009d9 R14: 00000000004cb40c R15: 000000000075bfd4