TCP: request_sock_TCPv6: Possible SYN flooding on port 20000. Sending cookies. Check SNMP counters. INFO: task kworker/1:8:12295 blocked for more than 120 seconds. Not tainted 4.16.0-rc7+ #368 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:8 D22272 12295 2 0x80000000 Workqueue: events cgwb_release_workfn Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x8fb/0x1ec0 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 bit_wait+0x18/0x90 kernel/sched/wait_bit.c:250 __wait_on_bit+0x88/0x130 kernel/sched/wait_bit.c:51 out_of_line_wait_on_bit+0x204/0x3a0 kernel/sched/wait_bit.c:64 wait_on_bit include/linux/wait_bit.h:84 [inline] wb_shutdown+0x335/0x430 mm/backing-dev.c:377 cgwb_release_workfn+0x8b/0x61d mm/backing-dev.c:520 process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113 worker_thread+0x223/0x1990 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 Showing all locks held in the system: 2 locks held by khungtaskd/869: #0: (rcu_read_lock){....}, at: [<00000000a97979f6>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000a97979f6>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<000000009c482377>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4397: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4398: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4399: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4400: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4401: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4402: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by syz-executor7/4466: #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] inode_lock_nested include/linux/fs.h:748 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] do_rmdir+0x380/0x5f0 fs/namei.c:3907 2 locks held by syz-executor3/4471: #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] inode_lock_nested include/linux/fs.h:748 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] do_rmdir+0x380/0x5f0 fs/namei.c:3907 2 locks held by syz-executor4/4472: #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] inode_lock_nested include/linux/fs.h:748 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] do_rmdir+0x380/0x5f0 fs/namei.c:3907 4 locks held by syz-executor1/4475: #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] inode_lock_nested include/linux/fs.h:748 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] do_rmdir+0x380/0x5f0 fs/namei.c:3907 #2: (&type->i_mutex_dir_key#3){++++}, at: [<000000006786de92>] inode_lock include/linux/fs.h:713 [inline] #2: (&type->i_mutex_dir_key#3){++++}, at: [<000000006786de92>] vfs_rmdir+0xd6/0x410 fs/namei.c:3848 #3: (cgroup_mutex){+.+.}, at: [<00000000c1422cdb>] cgroup_kn_lock_live+0x29e/0x580 kernel/cgroup/cgroup.c:1535 2 locks held by syz-executor2/4476: #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] inode_lock_nested include/linux/fs.h:748 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] do_rmdir+0x380/0x5f0 fs/namei.c:3907 2 locks held by kworker/1:8/12295: #0: ((wq_completion)"events"){+.+.}, at: [<000000000e17691e>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"events"){+.+.}, at: [<000000000e17691e>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"events"){+.+.}, at: [<000000000e17691e>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"events"){+.+.}, at: [<000000000e17691e>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: ((work_completion)(&wb->release_work)){+.+.}, at: [<0000000090d1c60c>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 2 locks held by syz-executor6/22449: #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#10){.+.+}, at: [<0000000031179b7a>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] inode_lock_nested include/linux/fs.h:748 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [<00000000b8aea8fd>] do_rmdir+0x380/0x5f0 fs/namei.c:3907 2 locks held by getty/24373: #0: (&tty->ldisc_sem){++++}, at: [<00000000c9edcc50>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000899b9bb3>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 3 locks held by kworker/0:10/29285: #0: ((wq_completion)"cgroup_destroy"){+.+.}, at: [<000000000e17691e>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"cgroup_destroy"){+.+.}, at: [<000000000e17691e>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"cgroup_destroy"){+.+.}, at: [<000000000e17691e>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"cgroup_destroy"){+.+.}, at: [<000000000e17691e>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: ((work_completion)(&css->destroy_work)){+.+.}, at: [<0000000090d1c60c>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (cgroup_mutex){+.+.}, at: [<00000000824b8910>] css_killed_work_fn+0x93/0x5c0 kernel/cgroup/cgroup.c:4967 1 lock held by syz-executor5/29341: #0: (event_mutex){+.+.}, at: [<0000000077043e54>] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor0/29356: #0: (&type->i_mutex_dir_key#3){++++}, at: [<000000003a8b38a2>] inode_lock_shared include/linux/fs.h:723 [inline] #0: (&type->i_mutex_dir_key#3){++++}, at: [<000000003a8b38a2>] lookup_slow+0x18e/0x4d0 fs/namei.c:1612 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 869 Comm: khungtaskd Not tainted 4.16.0-rc7+ #368 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 29284 Comm: kworker/0:9 Not tainted 4.16.0-rc7+ #368 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events rht_deferred_worker RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:778 [inline] RIP: 0010:lock_acquire+0x256/0x580 kernel/locking/lockdep.c:3923 RSP: 0018:ffff88019720ee00 EFLAGS: 00000082 RAX: dffffc0000000000 RBX: ffff8801c745c740 RCX: 0000000000000000 RDX: 1ffffffff0f5957d RSI: 00000000bc047aad RDI: 0000000000000082 RBP: ffff88019720eef8 R08: 1ffff10032e41d23 R09: 000000000000000c R10: ffff88019720ede0 R11: 0000000000000000 R12: 1ffff10032e41dc6 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa2d0d9a000 CR3: 0000000007a22002 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 debug_object_activate+0x1d7/0x730 lib/debugobjects.c:432 debug_work_activate kernel/workqueue.c:493 [inline] __queue_work+0x163/0x1230 kernel/workqueue.c:1382 queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1488 queue_work include/linux/workqueue.h:488 [inline] schedule_work include/linux/workqueue.h:546 [inline] rht_deferred_worker+0x2ba/0x1cd0 lib/rhashtable.c:436 process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113 worker_thread+0x223/0x1990 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 Code: 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 95 02 00 00 48 83 3d e1 cb 54 06 00 0f 84 d1 01 00 00 48 8b bd 20 ff ff ff 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 49 c7 04 04 00 00