INFO: task syz-executor2:32295 blocked for more than 140 seconds. Not tainted 4.19.0-rc3+ #236 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D23160 32295 22629 0x00000000 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473 schedule+0xfe/0x460 kernel/sched/core.c:3517 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:00007fd639f91c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fd639f926d4 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/985: #0: 00000000267c66e4 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4436 1 lock held by rsyslogd/5221: #0: 00000000a0618c2a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5311: #0: 00000000cacf92ee (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000037ee7b3b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5312: #0: 000000009390fe3e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000ed7d37bc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5313: #0: 00000000edf0b7d9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000cc16d885 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5314: #0: 000000007382cbcd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000077f634d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5315: #0: 0000000020380e7e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b4b6126e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5316: #0: 00000000b142e2af (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000007876544b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5317: #0: 000000001eba6bd3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000422fdc53 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-executor0/17530: 1 lock held by syz-executor5/21355: 2 locks held by syz-executor0/22638: #0: 00000000fdb8e931 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000f55dbb66 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor2/32262: #0: 00000000d5ca8f0a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000f96359cc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-executor2/32295: #0: 00000000d5ca8f0a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 1 lock held by syz-executor2/32311: #0: 000000005ce4cf34 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x53/0x120 fs/exec.c:1404 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 985 Comm: khungtaskd Not tainted 4.19.0-rc3+ #236 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+0x1c4/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed 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+0xb3e/0x1050 kernel/hung_task.c:265 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 Sending NMI from CPU 1 to CPUs 0: INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.041 msecs NMI backtrace for cpu 0 CPU: 0 PID: 5127 Comm: kworker/0:2 Not tainted 4.19.0-rc3+ #236 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_power_efficient gc_worker RIP: 0010:lock_acquire+0x1b6/0x520 kernel/locking/lockdep.c:3901 Code: 00 65 8b 05 dc 90 a0 7e 83 f8 3f 0f 87 87 02 00 00 89 c0 48 0f a3 05 f9 5a d0 08 0f 82 1b 02 00 00 4c 8b 8d 20 ff ff ff 6a 00 <44> 89 e2 45 89 f0 6a 00 44 89 e9 ff 75 10 41 57 48 8b bd 30 ff ff RSP: 0000:ffff8801218c73f0 EFLAGS: 00000086 RAX: 0000000000000000 RBX: 1ffff10024318e84 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88011fa969bc RBP: ffff8801218c74e8 R08: 0000000000000001 R09: 0000000000000082 R10: ffffed003b5c4732 R11: ffff8801dae23993 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f395b5cbdb8 CR3: 00000001c8587000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:302 [inline] gc_worker+0x2b6/0x1150 net/netfilter/nf_conntrack_core.c:1157 process_one_work+0xc90/0x1b90 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413