Buffer I/O error on dev loop0, logical block 6, lost async page write Buffer I/O error on dev loop0, logical block 7, lost async page write Buffer I/O error on dev loop0, logical block 8, lost async page write Buffer I/O error on dev loop0, logical block 9, lost async page write Buffer I/O error on dev loop0, logical block 10, lost async page write INFO: task syz-executor5:9596 blocked for more than 120 seconds. Not tainted 4.16.0-rc7+ #370 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D17712 9596 4472 0x00000004 Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x8fb/0x1ec0 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3557 __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 iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 sys_sync+0x120/0x1c0 fs/sync.c:117 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4548b9 RSP: 002b:00007f838445ac68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2 RAX: ffffffffffffffda RBX: 00007f838445b6d4 RCX: 00000000004548b9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000064b R14: 00000000006fb7a8 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:1/21: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000cd70a374>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000cd70a374>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000cd70a374>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000cd70a374>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000b4fd6861>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (&type->s_umount_key#33){++++}, at: [<000000004fb6531e>] trylock_super+0x20/0x100 fs/super.c:395 2 locks held by khungtaskd/869: #0: (rcu_read_lock){....}, at: [<0000000051b13610>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<0000000051b13610>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000f8481e75>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4390: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4391: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4392: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4393: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4394: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4395: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4396: #0: (&tty->ldisc_sem){++++}, at: [<00000000808b72ef>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000077dae528>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 1 lock held by syz-executor5/9596: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000a79d6179>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 1 lock held by syz-executor5/9620: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000d59bf7cf>] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1808 1 lock held by syz-executor5/9627: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000a79d6179>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 1 lock held by syz-executor6/9603: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000a79d6179>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 1 lock held by syz-executor6/9619: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000a79d6179>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 1 lock held by syz-executor6/9623: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000057596bcd>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 1 lock held by blkid/9612: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000057596bcd>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 869 Comm: khungtaskd Not tainted 4.16.0-rc7+ #370 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+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 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+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.16.0-rc7+ #370 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:773 [inline] RIP: 0010:arch_local_irq_save arch/x86/include/asm/paravirt.h:795 [inline] RIP: 0010:seqcount_lockdep_reader_access include/linux/seqlock.h:80 [inline] RIP: 0010:read_seqcount_begin include/linux/seqlock.h:164 [inline] RIP: 0010:ktime_get+0xd5/0x3a0 kernel/time/timekeeping.c:762 RSP: 0018:ffff8801db207c30 EFLAGS: 00000093 RAX: ffffffff87a2d200 RBX: dffffc0000000000 RCX: ffffffff81628905 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000082 RBP: ffff8801db207d18 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003b640f8a R13: ffff8801db207cf0 R14: ffff8801db207e68 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000007a22004 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tick_nohz_irq_enter kernel/time/tick-sched.c:1148 [inline] tick_irq_enter+0x9e/0x390 kernel/time/tick-sched.c:1169 irq_enter+0xb6/0xd0 kernel/softirq.c:346 scheduler_ipi+0x23d/0x820 kernel/sched/core.c:1794 smp_reschedule_interrupt+0xe6/0x650 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:881 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff87a07c38 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0f40f8a RCX: 0000000000000000 RDX: 1ffffffff0f59580 RSI: 0000000000000001 RDI: ffffffff87acac00 RBP: ffffffff87a07c38 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff87a07cf0 R14: ffffffff883b4820 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0xbf/0x430 arch/x86/kernel/process.c:354 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:345 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+0x104/0x120 kernel/sched/idle.c:351 rest_init+0xed/0xf0 init/main.c:437 start_kernel+0x7f1/0x819 init/main.c:717 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:239 Code: 48 c7 c0 e0 ab ac 87 48 c1 e8 03 80 3c 18 00 0f 85 bd 02 00 00 48 c7 c0 e0 ab ac 87 48 83 38 00 0f 84 63 02 00 00 e8 1b 40 0f 00 <9c> 58 0f 1f 44 00 00 49 89 c6 48 8b 85 30 ff ff ff 80 38 00 0f