kworker/dying (3971) used greatest stack depth: 13720 bytes left INFO: task syz-executor3:8473 blocked for more than 120 seconds. Not tainted 4.15.0-rc2+ #209 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D24320 8473 3321 0x00000004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3492 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601 block_ioctl+0xea/0x130 fs/block_dev.c:1860 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x1f/0x96 RIP: 0033:0x452a39 RSP: 002b:00007fc963a7fc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452a39 RDX: 000000002002df18 RSI: 0000000000004c04 RDI: 0000000000000018 RBP: 000000000000039b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2728 R13: 00000000ffffffff R14: 0000000000758098 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/674: #0: (rcu_read_lock){....}, at: [<000000003e010448>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000003e010448>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.?.?}, at: [<0000000051c42851>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554 2 locks held by getty/3066: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3067: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3068: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3069: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3070: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3071: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 1 lock held by syz-executor3/8473: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000ef507737>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor3/8479: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000ef507737>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 2 locks held by getty/8560: #0: (&tty->ldisc_sem){++++}, at: [<0000000094f7ec2f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a9a04587>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 674 Comm: khungtaskd Not tainted 4.15.0-rc2+ #209 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x37a/0x440 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc2+ #209 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0x549/0x47f0 kernel/locking/lockdep.c:3450 RSP: 0018:ffff8801db407768 EFLAGS: 00000002 RAX: 000000000000000e RBX: ffffffff85e2fc08 RCX: 0000000000000006 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff85e2fc2c RBP: ffff8801db407af0 R08: 0000000000000000 R09: 000000000000000e R10: 0000000000000000 R11: ffffffff87489d60 R12: ffffffff85e2f380 R13: 0000000000000034 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f39cc6f5140 CR3: 00000001d1392000 CR4: 00000000001406f0 Call Trace: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] ktime_get+0x12f/0x3a0 kernel/time/timekeeping.c:762 tick_nohz_irq_enter kernel/time/tick-sched.c:1120 [inline] tick_irq_enter+0x9e/0x390 kernel/time/tick-sched.c:1141 irq_enter+0xbd/0xe0 kernel/softirq.c:346 scheduler_ipi+0x246/0x830 kernel/sched/core.c:1793 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:819 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff85e07d08 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0bc0fa4 RCX: 0000000000000000 RDX: 1ffffffff0bd968c RSI: 0000000000000001 RDI: ffffffff85ecb460 RBP: ffffffff85e07d08 R08: ffffffff85be9ae0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff85e07dc0 R14: ffffffff865eaa20 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:348 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:339 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351 rest_init+0xed/0xf0 init/main.c:435 start_kernel+0x729/0x74f init/main.c:710 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: c1 e0 02 44 88 53 21 83 e1 f8 09 d1 09 c1 42 8d 04 cd 00 00 00 00 83 e1 f7 41 89 c9 41 09 c1 44 88 4b 22 0f b7 55 20 0f b7 43 22 e2 04 83 e0 0f 09 d0 48 89 fa 66 89 43 22 48 c1 ea 03 48 b8