kworker/dying (7) used greatest stack depth: 11448 bytes left INFO: task syz-executor4:1918 blocked for more than 140 seconds. Not tainted 4.18.0-rc8+ #184 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor4 D23672 1918 4480 0x00000004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x87c/0x1ec0 kernel/sched/core.c:3501 schedule+0xfb/0x450 kernel/sched/core.c:3545 schedule_timeout+0x1cc/0x260 kernel/time/timer.c:1777 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x430/0x8d0 kernel/sched/completion.c:136 flush_work+0x531/0x900 kernel/workqueue.c:2918 __cancel_work_timer+0x4bd/0x830 kernel/workqueue.c:2989 cancel_work_sync+0x17/0x20 kernel/workqueue.c:3025 p9_conn_destroy net/9p/trans_fd.c:860 [inline] p9_fd_close+0x36a/0x5b0 net/9p/trans_fd.c:886 p9_client_create+0xa9a/0x1770 net/9p/client.c:1077 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135 mount_fs+0xae/0x328 fs/super.c:1277 vfs_kern_mount.part.34+0xdc/0x4e0 fs/namespace.c:1037 vfs_kern_mount fs/namespace.c:1027 [inline] do_new_mount fs/namespace.c:2518 [inline] do_mount+0x581/0x30e0 fs/namespace.c:2848 ksys_mount+0x12d/0x140 fs/namespace.c:3064 __do_sys_mount fs/namespace.c:3078 [inline] __se_sys_mount fs/namespace.c:3075 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457089 Code: 08 e8 3b a9 fb ff 48 8b 44 24 20 48 8b 4c 24 18 48 8b 54 24 38 48 8b 7c 24 48 eb 8d 48 8b 6c 24 50 48 83 c4 58 c3 48 89 04 24 <48> 89 5c 24 08 e8 0d a9 fb ff 48 8b 44 24 40 48 8b 4c 24 48 48 8b RSP: 002b:00007f955ce30c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f955ce316d4 RCX: 0000000000457089 RDX: 00000000200003c0 RSI: 0000000020000380 RDI: 0000000000000000 RBP: 0000000000930140 R08: 00000000200004c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d2310 R14: 00000000004c7a36 R15: 0000000000000001 Showing all locks held in the system: 1 lock held by khungtaskd/774: #0: 000000005e5fc493 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4461 2 locks held by rs:main Q:Reg/4335: #0: 000000002f43fb9a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 000000003753f3c0 (sb_writers#6){.+.+}, at: file_start_write include/linux/fs.h:2738 [inline] #1: 000000003753f3c0 (sb_writers#6){.+.+}, at: vfs_write+0x452/0x560 fs/read_write.c:548 1 lock held by rsyslogd/4337: #0: 00000000b0f6f9fc (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/4428: #0: 000000004b2a9773 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000024be4cb4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4429: #0: 000000009ab96fa1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b84f69d9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4430: #0: 000000007a7f33ae (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000007721b97d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4431: #0: 0000000036a0bc49 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003eb9f66f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4432: #0: 000000005473e80a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000009503c291 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4433: #0: 00000000b7772c66 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e02434f2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4434: #0: 00000000a9d85069 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003cc5d46d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by kworker/1:6/1232: #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 0000000083dd1415 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb44/0x1ba0 kernel/workqueue.c:2124 #1: 000000008b4f289b ((work_completion)(&m->wq)){+.+.}, at: process_one_work+0xb9b/0x1ba0 kernel/workqueue.c:2128 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 774 Comm: khungtaskd Not tainted 4.18.0-rc8+ #184 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+0x1c9/0x2b4 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_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x9c4/0xf80 kernel/hung_task.c:252 kthread+0x345/0x410 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54