Buffer I/O error on dev loop0, logical block 0, lost async page write INFO: task blkid:4838 blocked for more than 120 seconds. Not tainted 4.15.0-rc7+ #172 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. blkid D23376 4838 3746 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: 0033:0x7f7b5e4952b0 RSP: 002b:00007fff7c0b3f88 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f7b5e4952b0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000028 R09: 0000000001680000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000019f4030 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000000000005 Showing all locks held in the system: 2 locks held by khungtaskd/746: #0: (rcu_read_lock){....}, at: [<00000000c87e647c>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000c87e647c>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<000000000e0209d4>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 2 locks held by getty/3655: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3656: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3657: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3658: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3659: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3660: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:5/8475: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000ff6fa40e>] process_one_work+0xaaf/0x1b10 kernel/workqueue.c:2083 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000e36335c0>] process_one_work+0xb01/0x1b10 kernel/workqueue.c:2087 #2: (&type->s_umount_key#27){.+.+}, at: [<00000000b15069bc>] trylock_super+0x20/0x100 fs/super.c:395 2 locks held by getty/3026: #0: (&tty->ldisc_sem){++++}, at: [<000000006ad585e5>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000007e61f4c4>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by blkid/4838: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000c5500072>] __blkdev_put+0xbc/0x7f0 fs/block_dev.c:1757 1 lock held by syz-executor6/5559: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000055c2112a>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 1 lock held by syz-executor6/5571: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000055c2112a>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 746 Comm: khungtaskd Not tainted 4.15.0-rc7+ #172 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+0x37/0x50 arch/x86/entry/entry_64.S:530 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc7+ #172 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:find_held_lock+0x11/0x1d0 kernel/locking/lockdep.c:3523 RSP: 0018:ffff8801db307950 EFLAGS: 00000002 RAX: 0000000000000001 RBX: ffffffff87f07200 RCX: ffff8801db3079d0 RDX: 0000000000000001 RSI: ffffffff87f08fc8 RDI: ffff8801d9f66300 RBP: ffff8801db307978 R08: 0000000000000000 R09: 000000000000000e R10: ffff8801db3079a0 R11: 0000000000000001 R12: 0000000000000000 R13: ffff8801d9f66300 R14: ffff8801db3079d0 R15: 1ffff1003b660f36 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001eb8000 CR3: 0000000006822005 CR4: 00000000001606e0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: __lock_release kernel/locking/lockdep.c:3683 [inline] lock_release+0x295/0xa40 kernel/locking/lockdep.c:3933 seqcount_lockdep_reader_access include/linux/seqlock.h:82 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] timekeeping_max_deferment+0x112/0x380 kernel/time/timekeeping.c:1465 tick_nohz_stop_sched_tick kernel/time/tick-sched.c:733 [inline] __tick_nohz_idle_enter+0x4cb/0x1640 kernel/time/tick-sched.c:926 tick_nohz_irq_exit+0x4e/0x60 kernel/time/tick-sched.c:986 tick_irq_exit kernel/softirq.c:387 [inline] irq_exit+0x1b6/0x200 kernel/softirq.c:407 scheduler_ipi+0x318/0x820 kernel/sched/core.c:1803 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:950 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9f77cb0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3eef99 RCX: 0000000000000000 RDX: 1ffffffff0d19178 RSI: 0000000000000001 RDI: ffffffff868c8bc0 RBP: ffff8801d9f77cb0 R08: ffffffff8666fae8 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9f77d68 R14: ffffffff87037da0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:355 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:346 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 start_secondary+0x40a/0x590 arch/x86/kernel/smpboot.c:268 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: b5 f0 fe ff ff e9 8b f9 ff ff 4c 89 f7 e8 c8 cb 51 00 e9 17 f9 ff ff 0f 1f 00 55 48 89 e5 41 57 41 56 41 55 41 54 44 8d 62 ff 53 <49> 89 f6 49 89 cf 49 63 c4 48 8d 04 80 48 83 ec 08 89 55 d0 4c