Buffer I/O error on dev loop0, logical block 16, async page read INFO: task syz-executor2:8259 blocked for more than 120 seconds. Not tainted 4.15.0-rc8-mm1+ #57 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D24304 8259 7563 0x00000004 Call Trace: context_switch kernel/sched/core.c:2845 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3421 schedule+0xf5/0x430 kernel/sched/core.c:3480 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3538 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 iterate_bdevs+0xc8/0x260 fs/block_dev.c:2144 sys_sync+0x120/0x1c0 fs/sync.c:117 entry_SYSCALL_64_fastpath+0x29/0xa0 RIP: 0033:0x452e99 RSP: 002b:00007f117df2bc58 EFLAGS: 00000212 ORIG_RAX: 00000000000000a2 RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452e99 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00000000000001a3 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f07e8 R13: 00000000ffffffff R14: 00007f117df2c6d4 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:4/187: #0: ((wq_completion)"writeback"){+.+.}, at: [<0000000093858b4f>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<0000000036bff003>] process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<00000000ddd444d5>] trylock_super+0x20/0x100 fs/super.c:395 2 locks held by khungtaskd/747: #0: (rcu_read_lock){....}, at: [<0000000012ae60fa>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<0000000012ae60fa>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<0000000044a6f0a8>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 1 lock held by rsyslogd/3508: #0: (&f->f_pos_lock){+.+.}, at: [<000000001e8e718e>] __fdget_pos+0x12b/0x190 fs/file.c:765 2 locks held by getty/3630: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3631: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3632: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3633: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3634: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3635: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3636: #0: (&tty->ldisc_sem){++++}, at: [<00000000f40ab3e1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000caefe457>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by blkid/7568: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000905db331>] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1792 1 lock held by syz-executor2/8259: #0: (&bdev->bd_mutex){+.+.}, at: [<000000005a4194d0>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2144 1 lock held by syz-executor2/8287: #0: (&bdev->bd_mutex){+.+.}, at: [<000000005a4194d0>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2144 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 747 Comm: khungtaskd Not tainted 4.15.0-rc8-mm1+ #57 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