Buffer I/O error on dev loop0, logical block 9, lost async page write INFO: task syz-executor1:6641 blocked for more than 120 seconds. Not tainted 4.9.90-gdd1e37e #66 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D26656 6641 3864 0x00000004 ffff8801cd896000 0000000000000000 ffff8801cf0ddf80 ffffffff84429880 ffff8801db221b98 ffff8801cd56fcb8 ffffffff838a75cb 0000000000000000 0000000000000007 00ff8801cd896000 ffff8801db222468 ffff8801db222490 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3551 [] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3584 [] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [] mutex_lock_nested+0x312/0x870 kernel/locking/mutex.c:621 [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 [] sys_sync+0xe1/0x170 fs/sync.c:116 [] do_syscall_64+0x1a4/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 3 locks held by kworker/u4:2/103: #0: ("writeback"){.+.+.+}, at: [] work_static include/linux/workqueue.h:186 [inline] #0: ("writeback"){.+.+.+}, at: [] set_work_data kernel/workqueue.c:617 [inline] #0: ("writeback"){.+.+.+}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: ("writeback"){.+.+.+}, at: [] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085 #1: ((&(&wb->dwork)->work)){+.+.+.}, at: [] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089 #2: (&type->s_umount_key#22){.+.+..}, at: [] trylock_super+0x20/0x100 fs/super.c:393 2 locks held by khungtaskd/515: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x125/0xa70 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336 2 locks held by getty/3781: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133 1 lock held by syz-executor1/6641: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by syz-executor1/6664: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_put+0xbc/0x7e0 fs/block_dev.c:1579 1 lock held by syz-executor1/6687: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by blkid/6683: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.90-gdd1e37e #66 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d85c7d00 ffffffff81d94ee9 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810bb920 ffff8801d85c7d38 ffffffff81da000d 0000000000000001 0000000000000000 ffff8801cd5a1c18 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6f0/0xa70 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff838b7116