Buffer I/O error on dev loop0, logical block 16, async page read INFO: task syz-executor2:30037 blocked for more than 120 seconds. Not tainted 4.15.0-rc3-next-20171214+ #67 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D 0 30037 3359 0x80000004 Call Trace: context_switch kernel/sched/core.c:2800 [inline] __schedule+0x30b/0xaf0 kernel/sched/core.c:3376 schedule+0x2e/0x90 kernel/sched/core.c:3435 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0xfe/0x170 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] down_read+0x4c/0x70 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:510 [inline] do_exit+0x1c4/0x1050 kernel/exit.c:856 do_group_exit+0x60/0x100 kernel/exit.c:972 get_signal+0x36c/0xad0 kernel/signal.c:2337 do_signal+0x23/0x670 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x13c/0x160 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x1b4/0x1e0 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x94/0x96 RIP: 0033:0x452a8a RSP: 002b:0000000000a6f758 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 0000000000452a8a RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000 RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/672: #0: (rcu_read_lock){....}, at: [<000000003fabcd7e>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000003fabcd7e>] watchdog+0xbf/0x750 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000431ef21b>] debug_show_all_locks+0x3d/0x1a0 kernel/locking/lockdep.c:4464 1 lock held by khugepaged/678: #0: (&mm->mmap_sem){++++}, at: [<000000009ce94803>] khugepaged_scan_mm_slot mm/khugepaged.c:1676 [inline] #0: (&mm->mmap_sem){++++}, at: [<000000009ce94803>] khugepaged_do_scan mm/khugepaged.c:1809 [inline] #0: (&mm->mmap_sem){++++}, at: [<000000009ce94803>] khugepaged+0x526/0x2f60 mm/khugepaged.c:1854 1 lock held by rsyslogd/2968: #0: (&f->f_pos_lock){+.+.}, at: [<00000000cc680ca5>] __fdget_pos+0x5b/0x70 fs/file.c:765 2 locks held by getty/3090: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 2 locks held by getty/3091: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 2 locks held by getty/3092: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 2 locks held by getty/3093: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 2 locks held by getty/3094: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 2 locks held by getty/3095: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 2 locks held by getty/3096: #0: (&tty->ldisc_sem){++++}, at: [<00000000e97c64b6>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000046b6ef44>] n_tty_read+0xce/0xa40 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:4/3849: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000b1f81a3a>] set_work_data kernel/workqueue.c:617 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000b1f81a3a>] set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000b1f81a3a>] process_one_work+0x1f2/0x7a0 kernel/workqueue.c:2083 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000b1f81a3a>] set_work_data kernel/workqueue.c:617 [inline] #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000b1f81a3a>] set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline] #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000b1f81a3a>] process_one_work+0x1f2/0x7a0 kernel/workqueue.c:2083 #2: (&type->s_umount_key#25){++++}, at: [<0000000043ae4adf>] trylock_super+0x20/0x80 fs/super.c:395 1 lock held by blkid/29240: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000e5d770cb>] blkdev_put+0x24/0x1b0 fs/block_dev.c:1793 1 lock held by syz-executor2/30037: #0: (&mm->mmap_sem){++++}, at: [<0000000070b006da>] exit_mm kernel/exit.c:510 [inline] #0: (&mm->mmap_sem){++++}, at: [<0000000070b006da>] do_exit+0x1c4/0x1050 kernel/exit.c:856 1 lock held by syz-executor2/30038: #0: (&mm->mmap_sem){++++}, at: [<0000000070b006da>] exit_mm kernel/exit.c:510 [inline] #0: (&mm->mmap_sem){++++}, at: [<0000000070b006da>] do_exit+0x1c4/0x1050 kernel/exit.c:856 1 lock held by syz-executor2/30040: #0: (&mm->mmap_sem){++++}, at: [<00000000ed34806e>] vm_mmap_pgoff+0x9a/0x110 mm/util.c:331 1 lock held by syz-executor7/30084: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000575c62ad>] iterate_bdevs+0xa4/0x180 fs/block_dev.c:2145 1 lock held by syz-executor7/30102: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000575c62ad>] iterate_bdevs+0xa4/0x180 fs/block_dev.c:2145 1 lock held by syz-executor6/30123: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000c3724ca4>] __blkdev_get+0x80/0x660 fs/block_dev.c:1439 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 672 Comm: khungtaskd Not tainted 4.15.0-rc3-next-20171214+ #67 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+0xe9/0x14b lib/dump_stack.c:53 nmi_cpu_backtrace+0x149/0x150 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x101/0x150 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+0x562/0x750 kernel/hung_task.c:249 kthread+0x149/0x170 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 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