INFO: task syz-executor0:28626 blocked for more than 140 seconds. Not tainted 4.19.0-rc3-next-20180913+ #73 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D25208 28626 5562 0x00000000 Call Trace: context_switch kernel/sched/core.c:2830 [inline] __schedule+0x86c/0x1ed0 kernel/sched/core.c:3479 schedule+0xfe/0x460 kernel/sched/core.c:3523 schedule_timeout+0x1cc/0x260 kernel/time/timer.c:1780 down_read_failed drivers/tty/tty_ldsem.c:224 [inline] __ldsem_down_read_nested+0x538/0xb80 drivers/tty/tty_ldsem.c:318 ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:263 tty_ioctl+0x512/0x1820 drivers/tty/tty_io.c:2650 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4572d9 Code: fd b4 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fbf4ee8bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fbf4ee8c6d4 RCX: 00000000004572d9 RDX: 0000000020000140 RSI: 0000000000004b62 RDI: 0000000000000005 RBP: 0000000000930320 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004cf3b8 R14: 00000000004c56c1 R15: 0000000000000004 Showing all locks held in the system: 1 lock held by khungtaskd/984: #0: 00000000d7e7f5a7 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4435 1 lock held by rsyslogd/5426: #0: 00000000ca30f814 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5516: #0: 00000000c20e41d8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d773fe34 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5517: #0: 00000000928897fb (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000c99c188b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5518: #0: 000000008646cabd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000c84d5cef (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5519: #0: 000000006aa2eff8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000b2d0977 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5520: #0: 00000000cdae8a9d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000004b86edfc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5521: #0: 00000000cc45d305 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000050cb8a18 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5522: #0: 0000000017a31cd1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000088ac65e9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by udevd/5524: #0: 0000000000e0b8f6 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1125 [inline] #0: 0000000000e0b8f6 (&rq->lock){-.-.}, at: __schedule+0x236/0x1ed0 kernel/sched/core.c:3417 #1: 00000000d7e7f5a7 (rcu_read_lock){....}, at: trace_sched_stat_runtime include/trace/events/sched.h:418 [inline] #1: 00000000d7e7f5a7 (rcu_read_lock){....}, at: update_curr+0x383/0xbe0 kernel/sched/fair.c:830 2 locks held by syz-executor3/10139: #0: 00000000d4ca0842 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000033f393b1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor2/25282: #0: 00000000aee04d33 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000002be68e49 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor0/28593: #0: 00000000d75288a1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000dec32a1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-executor0/28625: #0: 000000008fa1a1e7 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x53/0x120 fs/exec.c:1404 1 lock held by syz-executor0/28626: #0: 00000000d75288a1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 1 lock held by syz-executor5/531: #0: 00000000efa11c17 (&sb->s_type->i_mutex_key#11){+.+.}, at: inode_lock include/linux/fs.h:745 [inline] #0: 00000000efa11c17 (&sb->s_type->i_mutex_key#11){+.+.}, at: __sock_release+0x8b/0x250 net/socket.c:579 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 984 Comm: khungtaskd Not tainted 4.19.0-rc3-next-20180913+ #73 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+0x1d3/0x2c4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1c2/0x22c 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb39/0x1050 kernel/hung_task.c:265 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 5563 Comm: syz-executor5 Not tainted 4.19.0-rc3-next-20180913+ #73 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:debug_lockdep_rcu_enabled kernel/rcu/update.c:248 [inline] RIP: 0010:rcu_read_lock_sched_held+0x27/0x120 kernel/rcu/update.c:110 Code: 00 00 00 48 c7 c7 54 8a 51 8a 55 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 89 e5 53 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 <83> c0 03 38 d0 7c 08 84 d2 0f 85 aa 00 00 00 8b 0d 88 d5 ea 08 85 RSP: 0018:ffff880140ad7478 EFLAGS: 00000002 RAX: 0000000000000004 RBX: ffff8801dac2da00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff83904c38 RDI: ffffffff8a518a54 RBP: ffff880140ad7480 R08: ffff880140aca0c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff880140ad7808 R13: 1ffff1002815aec9 R14: 0000000000000000 R15: ffff880140aca0c0 FS: 0000000001bb7940(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001713e80 CR3: 0000000140a73000 CR4: 00000000001406f0 Call Trace: trace_rcu_utilization include/trace/events/rcu.h:21 [inline] rcu_note_context_switch+0x12ad/0x2150 kernel/rcu/tree_plugin.h:335 __schedule+0x22e/0x1ed0 kernel/sched/core.c:3407 schedule+0xfe/0x460 kernel/sched/core.c:3523 freezable_schedule include/linux/freezer.h:172 [inline] do_nanosleep+0x21e/0x750 kernel/time/hrtimer.c:1688 hrtimer_nanosleep+0x2d4/0x620 kernel/time/hrtimer.c:1742 __do_sys_nanosleep kernel/time/hrtimer.c:1776 [inline] __se_sys_nanosleep kernel/time/hrtimer.c:1763 [inline] __x64_sys_nanosleep+0x1e7/0x280 kernel/time/hrtimer.c:1763 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x482d90 Code: 00 00 48 c7 c0 d4 ff ff ff 64 c7 00 16 00 00 00 31 c0 eb be 66 0f 1f 44 00 00 83 3d c1 36 5c 00 00 75 14 b8 23 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 14 fa f8 ff c3 48 83 ec 08 e8 ba 70 fd ff RSP: 002b:00007fffec7e5138 EFLAGS: 00000246 ORIG_RAX: 0000000000000023 RAX: ffffffffffffffda RBX: 00000000002037a0 RCX: 0000000000482d90 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fffec7e5140 RBP: 0000000000001c8d R08: 0000000000000001 R09: 0000000001bb7940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006 R13: 000000000020375e R14: 0000000000000b04 R15: badc0ffeebadface