INFO: task kworker/1:4:21768 blocked for more than 120 seconds. Not tainted 4.17.0-rc1+ #10 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:4 D22840 21768 2 0x80000000 Workqueue: events cgwb_release_workfn Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 bit_wait+0x18/0x90 kernel/sched/wait_bit.c:197 __wait_on_bit+0xb3/0x130 kernel/sched/wait_bit.c:48 out_of_line_wait_on_bit+0x204/0x3a0 kernel/sched/wait_bit.c:63 wait_on_bit include/linux/wait_bit.h:76 [inline] wb_shutdown+0x370/0x470 mm/backing-dev.c:366 cgwb_release_workfn+0x87/0x750 mm/backing-dev.c:509 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Showing all locks held in the system: 2 locks held by khungtaskd/891: #0: 00000000b7b66c23 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000b7b66c23 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000e0d4e017 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4513: #0: 00000000618fe714 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f4045ad7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4514: #0: 000000004f2b4b20 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c80ab4cc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4515: #0: 000000002a8a6c6f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000aaa294d5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4516: #0: 00000000c2ab7d75 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c0be1c56 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4517: #0: 00000000c557aee4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000087f7cf14 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4518: #0: 000000006513cac1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000088c61bae (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4519: #0: 000000008c375d6a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000004aa2ab1b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/1:4/21768: #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000004383d835 ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 000000001129b1b1 ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 1 lock held by syz-executor0/8841: #0: 000000009c557cee (&vcpu->mutex){+.+.}, at: kvm_vcpu_ioctl+0x1e2/0x12e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2542 3 locks held by syz-executor5/8835: #0: 00000000d8a6749c (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 #1: 00000000a0b4515e (sb_writers#6){.+.+}, at: file_start_write include/linux/fs.h:2718 [inline] #1: 00000000a0b4515e (sb_writers#6){.+.+}, at: vfs_write+0x452/0x560 fs/read_write.c:548 #2: 000000000e43656f (&sb->s_type->i_mutex_key#11){++++}, at: inode_lock include/linux/fs.h:713 [inline] #2: 000000000e43656f (&sb->s_type->i_mutex_key#11){++++}, at: generic_file_write_iter+0xe5/0x850 mm/filemap.c:3290 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 891 Comm: khungtaskd Not tainted 4.17.0-rc1+ #10 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+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 8844 Comm: syz-executor3 Not tainted 4.17.0-rc1+ #10 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:inode_init_always+0x60f/0xd30 fs/inode.c:164 RSP: 0018:ffff88018ddaf9f8 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 1ffff10031bb5f41 RCX: 0000000000000000 RDX: 1ffff10039daf791 RSI: 0000000000000004 RDI: ffff8801ced7bc8c RBP: ffff88018ddafb50 R08: ffffed0039daf79d R09: ffffed0039daf79c R10: ffffed0039daf79c R11: ffff8801ced7bce3 R12: ffff8801d9470c40 R13: ffff88018ddafb28 R14: 1ffff10031bb5f4d R15: ffff8801ced7baf0 FS: 00007f25f27fd700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020001480 CR3: 00000001b50da000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: alloc_inode+0x80/0x190 fs/inode.c:216 new_inode_pseudo+0x69/0x1a0 fs/inode.c:894 sock_alloc+0x41/0x270 net/socket.c:564 __sock_create+0x161/0x920 net/socket.c:1249 sock_create net/socket.c:1325 [inline] __sys_socket+0x100/0x250 net/socket.c:1355 __do_sys_socket net/socket.c:1364 [inline] __se_sys_socket net/socket.c:1362 [inline] __x64_sys_socket+0x73/0xb0 net/socket.c:1362 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455389 RSP: 002b:00007f25f27fcc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 00007f25f27fd6d4 RCX: 0000000000455389 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000015 RBP: 000000000072bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000061e R14: 00000000006fc370 R15: 0000000000000001 Code: 00 00 00 48 89 fa 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 11 05 00 00 49 8d bf 9c 01 00 00 48 b8 00 00 00 00 00 fc ff df <41> c7 87 98 01 00 00 00 00 00 00 48 89 fa 48 c1 ea 03 0f b6 14