Buffer I/O error on dev loop0, logical block 3, lost async page write INFO: task syz-executor2:21457 blocked for more than 120 seconds. Not tainted 4.15.0-rc8+ #180 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D23344 21457 4489 0x20020004 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+0x26/0x30 mm/filemap.c:458 fdatawrite_one_bdev+0x50/0x70 fs/sync.c:85 iterate_bdevs+0x109/0x260 fs/block_dev.c:2147 sys_sync+0x112/0x1c0 fs/sync.c:116 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 RIP: 0023:0xf7fe6c79 RSP: 002b:00000000f77e208c EFLAGS: 00000296 ORIG_RAX: 0000000000000024 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:1/21: #0: ((wq_completion)"writeback"){+.+.}, at: [<000000007c024f50>] process_one_work+0xaaf/0x1b10 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<000000007c286c90>] process_one_work+0xb01/0x1b10 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<000000000a7aa9da>] trylock_super+0x20/0x100 fs/super.c:395 2 locks held by khungtaskd/747: #0: (rcu_read_lock){....}, at: [<000000008244ce43>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000008244ce43>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<0000000099c1a256>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 2 locks held by getty/3626: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3627: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3628: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3629: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3630: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3631: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/19540: #0: (&tty->ldisc_sem){++++}, at: [<000000008c19396f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000003998dbba>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by blkid/21414: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000fe1c8db8>] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1793 1 lock held by syz-executor2/21457: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000052153db1>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 1 lock held by syz-executor2/21477: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000052153db1>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 747 Comm: khungtaskd Not tainted 4.15.0-rc8+ #180 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 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54