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_io_error: 119 callbacks suppressed Buffer I/O error on dev loop0, logical block 8176, async page read INFO: task syz-executor2:18544 blocked for more than 120 seconds. Not tainted 4.9.94-g8683408 #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D28264 18544 3841 0x00000004 ffff8801d7674800 ffff8801b9ccd500 ffff8801b98b8540 ffff8801a1610000 ffff8801db221b98 ffff88019cbcf940 ffffffff838c040d 1ffff10033979f1c ffffffff85351d98 0000000041b58ab3 00ffffff841a49d8 ffff8801db222468 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3557 [] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768 [] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180 [] 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_keep_errors+0x63/0x80 mm/filemap.c:511 [] fdatawait_one_bdev+0x50/0x70 fs/sync.c:94 [] iterate_bdevs+0x10c/0x260 fs/block_dev.c:1978 [] sys_sync+0xe1/0x170 fs/sync.c:116 [] 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/u4:9/8529: #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 1 lock held by blkid/16920: #0: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_put+0x2a/0x560 fs/block_dev.c:1621 1 lock held by syz-executor2/18544: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by syz-executor2/18565: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.94-g8683408 #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d855fd08 ffffffff81d9b509 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d855fd40 ffffffff81da6837 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 0xffffffff838cff16