Buffer I/O error on dev loop0, logical block 0, async page read INFO: task syz-executor1:7657 blocked for more than 120 seconds. Not tainted 4.14.0-rc4+ #124 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D17744 7657 3076 0x00000004 Call Trace: context_switch kernel/sched/core.c:2790 [inline] __schedule+0x8eb/0x2080 kernel/sched/core.c:3366 schedule+0xf5/0x430 kernel/sched/core.c:3425 io_schedule+0x1c/0x70 kernel/sched/core.c:5032 __blkdev_direct_IO_simple+0x74f/0xee0 fs/block_dev.c:253 blkdev_direct_IO+0xc8a/0x1000 fs/block_dev.c:440 generic_file_read_iter+0x4d2/0x2900 mm/filemap.c:2230 blkdev_read_iter+0x105/0x170 fs/block_dev.c:1923 call_read_iter include/linux/fs.h:1764 [inline] generic_file_splice_read+0x3ff/0x7c0 fs/splice.c:307 do_splice_to+0x110/0x170 fs/splice.c:880 splice_direct_to_actor+0x242/0x820 fs/splice.c:952 do_splice_direct+0x2a7/0x3d0 fs/splice.c:1061 do_sendfile+0x5d5/0xe90 fs/read_write.c:1433 SYSC_sendfile64 fs/read_write.c:1488 [inline] SyS_sendfile64+0xbd/0x160 fs/read_write.c:1480 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4520a9 RSP: 002b:00007f1d07113c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 00000000004520a9 RDX: 00000000200ddff8 RSI: 0000000000000016 RDI: 0000000000000016 RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000100000001 R11: 0000000000000216 R12: 00000000004b9857 R13: 00000000ffffffff R14: 0000000000000016 R15: 000000000000540f Showing all locks held in the system: 2 locks held by khungtaskd/643: #0: (rcu_read_lock){....}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4552 1 lock held by rsyslogd/2872: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x131/0x1a0 fs/file.c:767 2 locks held by getty/2954: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2955: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2956: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2957: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2958: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2959: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2960: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 643 Comm: khungtaskd Not tainted 4.14.0-rc4+ #124 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 nmi_cpu_backtrace+0x20e/0x240 lib/nmi_backtrace.c:102 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:61 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 trigger_all_cpu_backtrace include/linux/nmi.h:137 [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+0x39c/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.0-rc4+ #124 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d9f8a300 task.stack: ffff8801d9f90000 RIP: 0010:update_stack_state+0x0/0x700 include/linux/compiler.h:290 RSP: 0018:ffff8801db306900 EFLAGS: 00000002 RAX: 0000000000000000 RBX: ffff8801db306958 RCX: 0000000000000002 RDX: 0000000000000004 RSI: ffff8801db306948 RDI: ffff8801db306958 RBP: ffff8801db306948 R08: 00000000000164e0 R09: ffff8801db306958 R10: 000000000000000b R11: ffffed003b660d35 R12: ffff8801db306948 R13: ffff8801d9f8a300 R14: ffff8801db306980 R15: ffff8801db3069d0 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdb6c758000 CR3: 00000001ce12f000 CR4: 00000000001406e0 Call Trace: unwind_start arch/x86/include/asm/unwind.h:50 [inline] __save_stack_trace+0x4a/0xd0 arch/x86/kernel/stacktrace.c:43 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 add_xhlock kernel/locking/lockdep.c:4875 [inline] check_add_xhlock kernel/locking/lockdep.c:4898 [inline] lock_acquire_crosslock kernel/locking/lockdep.c:4970 [inline] __lock_acquire+0x20fd/0x4620 kernel/locking/lockdep.c:3501 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:159 rq_lock_irqsave kernel/sched/sched.h:1714 [inline] update_blocked_averages+0x2ae/0x4a30 kernel/sched/fair.c:7014 rebalance_domains+0x145/0xcc0 kernel/sched/fair.c:8790 run_rebalance_domains+0x378/0x770 kernel/sched/fair.c:9051 __do_softirq+0x29d/0xbb2 kernel/softirq.c:284 invoke_softirq kernel/softirq.c:364 [inline] irq_exit+0x1d3/0x210 kernel/softirq.c:405 scheduler_ipi+0x165/0x460 kernel/sched/core.c:1794 smp_reschedule_interrupt+0xf2/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:794 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53 RSP: 0018:ffff8801d9f97da8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3f2fb8 RCX: 0000000000000000 RDX: 1ffffffff0b59330 RSI: 0000000000000001 RDI: ffffffff85ac9980 RBP: ffff8801d9f97da8 R08: ffffffff857b4a68 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85ac9970 R13: ffff8801d9f97e60 R14: 0000000000000000 R15: ffffffff85ac9960 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:341 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:332 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24e/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351 start_secondary+0x2ea/0x3f0 arch/x86/kernel/smpboot.c:278 secondary_startup_64+0xa5/0xa5 arch/x86/kernel/head_64.S:235 Code: e8 46 61 73 00 eb a4 4c 89 e7 e8 5c 61 73 00 eb e6 4c 89 e7 e8 52 61 73 00 eb b8 48 8b 07 55 48 89 e5 48 89 06 5d c3 0f 1f 40 00 <55> 48 ba 00 00 00 00 00 fc ff df 48 89 e5 41 57 41 56 41 55 41