Buffer I/O error on dev loop0, logical block 0, lost async page write INFO: task blkid:26015 blocked for more than 120 seconds. Not tainted 4.15.0+ #285 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. blkid D23376 26015 4184 0x00000004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 io_schedule+0x1c/0x70 kernel/sched/core.c:5042 wait_on_page_bit_common mm/filemap.c:1100 [inline] __lock_page+0x574/0x720 mm/filemap.c:1273 lock_page include/linux/pagemap.h:483 [inline] write_cache_pages+0xb2b/0x14a0 mm/page-writeback.c:2206 generic_writepages+0xe9/0x150 mm/page-writeback.c:2325 blkdev_writepages+0x1d/0x30 fs/block_dev.c:1939 do_writepages+0xff/0x170 mm/page-writeback.c:2340 __filemap_fdatawrite_range+0x32f/0x460 mm/filemap.c:445 __filemap_fdatawrite mm/filemap.c:453 [inline] filemap_fdatawrite mm/filemap.c:458 [inline] filemap_write_and_wait+0x59/0xd0 mm/filemap.c:617 __sync_blockdev fs/block_dev.c:448 [inline] sync_blockdev.part.28+0x50/0x70 fs/block_dev.c:457 sync_blockdev fs/block_dev.c:444 [inline] __blkdev_put+0x18b/0x7f0 fs/block_dev.c:1763 blkdev_put+0x85/0x4f0 fs/block_dev.c:1835 blkdev_close+0x8b/0xb0 fs/block_dev.c:1842 __fput+0x327/0x7e0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x9e/0xa0 RIP: 0033:0x7f75dbe082b0 RSP: 002b:00007ffe295c8b08 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f75dbe082b0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000028 R09: 0000000001680000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000227e030 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000000000005 Showing all locks held in the system: 2 locks held by khungtaskd/760: #0: (rcu_read_lock){....}, at: [<000000000dd79440>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000000dd79440>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<0000000066878808>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4465 2 locks held by getty/4175: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4176: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4177: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4178: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4179: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4180: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4181: #0: (&tty->ldisc_sem){++++}, at: [<0000000063866162>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f8ddd644>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:7/5518: #0: ((wq_completion)"writeback"){+.+.}, at: [<000000001b4e070c>] process_one_work+0xaaf/0x1b10 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000331f0551>] process_one_work+0xb01/0x1b10 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<00000000b12f07e6>] trylock_super+0x20/0x100 fs/super.c:395 1 lock held by blkid/26015: #0: (&bdev->bd_mutex){+.+.}, at: [<000000006de4f6ac>] __blkdev_put+0xbc/0x7f0 fs/block_dev.c:1757 1 lock held by syz-executor7/26113: #0: (&bdev->bd_mutex){+.+.}, at: [<000000005e6e2476>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 1 lock held by syz-executor7/26119: #0: (&bdev->bd_mutex){+.+.}, at: [<000000005e6e2476>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 760 Comm: khungtaskd Not tainted 4.15.0+ #285 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+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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:541 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54