INFO: task syz-executor5:28074 blocked for more than 140 seconds. Not tainted 4.14.70+ #6 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D29752 28074 28058 0x00000000 Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1718 down_read_failed drivers/tty/tty_ldsem.c:242 [inline] __ldsem_down_read_nested+0x2ca/0x5b0 drivers/tty/tty_ldsem.c:332 tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 tty_ioctl+0x4cb/0x13e0 drivers/tty/tty_io.c:2649 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1a0/0x1030 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7e/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4572d9 RSP: 002b:00007f2c5f02fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f2c5f0306d4 RCX: 00000000004572d9 RDX: 0000000000000004 RSI: 0000000000004b4e RDI: 0000000000000009 RBP: 00000000009301e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004cf478 R14: 00000000004c5742 R15: 0000000000000002 Showing all locks held in the system: 1 lock held by khungtaskd/23: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x74/0x20f kernel/locking/lockdep.c:4541 2 locks held by getty/1753: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142 2 locks held by syz-executor2/23764: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142 2 locks held by syz-executor1/27398: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142 2 locks held by syz-executor5/28057: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142 1 lock held by syz-executor5/28074: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.70+ #6 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x11b lib/dump_stack.c:53 nmi_cpu_backtrace.cold.0+0x47/0x85 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x121/0x146 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x574/0xa70 kernel/hung_task.c:252 kthread+0x348/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 408 Comm: syz-executor5 Not tainted 4.14.70+ #6 task: ffff8800ab392f00 task.stack: ffff8801c7a48000 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:trace_hardirqs_on_caller+0x336/0x520 kernel/locking/lockdep.c:2927 RSP: 0018:ffff8801c7a4fef0 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff8800ab392f00 RCX: 0000000000000000 RDX: 1ffff100156726de RSI: 0000000000000001 RDI: ffff8800ab3936f0 RBP: 0000000000022281 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800ab392f00 R13: ffff8801c7a4ffd0 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f2c5f072700(0000) GS:ffff8801dba00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f38c9fc6db8 CR3: 0000000101bac001 CR4: 00000000001606b0 Call Trace: do_syscall_64+0x43/0x4b0 arch/x86/entry/common.c:277 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4572d9 RSP: 002b:00007f2c5f071cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00000000009300a8 RCX: 00000000004572d9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000009300a8 RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000009300ac R13: 00007fff2048383f R14: 00007f2c5f0729c0 R15: 0000000000000000 Code: 00 00 00 fc ff df 89 ab d8 07 00 00 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 25 01 00 00 89 ab f0 07 00 00 65 48 8b 1c 25 c0 de 01 00 <48> 8d bb 2c 08 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48