Buffer I/O error on dev loop0, logical block 64, async page read INFO: task syz-executor2:24882 blocked for more than 120 seconds. Not tainted 4.9.92-g7cd9561 #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D27288 24882 3840 0x00000004 ffff880196dd6000 0000000000000000 ffff8801cb7f8a80 ffffffff84429880 ffff8801db221b98 ffff8801b9fff4f0 ffffffff838c49cd 0000000041b58ab3 ffffffff841a4570 ffffffff81233c60 00ffffff814635a0 ffff8801db222468 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3556 [] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768 [] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5178 [] io_schedule include/linux/sched.h:460 [inline] [] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582 [] __wait_on_bit+0x93/0x120 kernel/sched/wait.c:383 [] wait_on_page_bit+0x130/0x140 mm/filemap.c:802 [] wait_on_page_writeback include/linux/pagemap.h:526 [inline] [] __filemap_fdatawait_range+0x1c1/0x290 mm/filemap.c:453 [] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:483 [] filemap_write_and_wait_range+0x85/0xb0 mm/filemap.c:584 [] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369 [] vfs_fsync_range+0x10c/0x260 fs/sync.c:195 [] generic_write_sync include/linux/fs.h:2590 [inline] [] blkdev_write_iter+0x2a9/0x370 fs/block_dev.c:1720 [] do_iter_readv_writev+0x3d4/0x4b0 fs/read_write.c:695 [] do_readv_writev+0x2f6/0x7a0 fs/read_write.c:871 [] vfs_writev+0x87/0xc0 fs/read_write.c:910 [] do_pwritev+0x197/0x240 fs/read_write.c:997 [] SYSC_pwritev fs/read_write.c:1044 [inline] [] SyS_pwritev+0x30/0x40 fs/read_write.c:1039 [] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 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+0x11c/0xa20 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336 2 locks held by getty/3741: #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+0x202/0x16b0 drivers/tty/n_tty.c:2133 3 locks held by kworker/u4:29/6854: #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+0x6ee/0x1500 kernel/workqueue.c:2085 #1: ((&(&wb->dwork)->work)){+.+.+.}, at: [] process_one_work+0x728/0x1500 kernel/workqueue.c:2089 #2: (&type->s_umount_key#29){++++..}, at: [] trylock_super+0x20/0xf0 fs/super.c:393 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.92-g7cd9561 #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d87f7d08 ffffffff81d9c489 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810b7d90 ffff8801d87f7d40 ffffffff81da77c7 0000000000000001 0000000000000000 0000000000000002 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12a/0x14f 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+0x6b4/0xa20 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 0xffffffff838d44d6