Buffer I/O error on dev loop0, logical block 1, async page read Buffer I/O error on dev loop0, logical block 3, async page read kworker/dying (44) used greatest stack depth: 8440 bytes left INFO: task syz-executor7:21889 blocked for more than 120 seconds. Not tainted 4.16.0+ #19 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D20640 21889 4562 0x00000006 Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x807/0x1e40 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3607 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xe38/0x17f0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 blkdev_put+0x34/0x540 fs/block_dev.c:1810 blkdev_close+0x8b/0xb0 fs/block_dev.c:1859 __fput+0x34d/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 get_signal+0x1543/0x1960 kernel/signal.c:2299 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x792/0x9d0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455259 RSP: 002b:00007f96b03cac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: fffffffffffffe00 RBX: 00007f96b03cb6d4 RCX: 0000000000455259 RDX: 0000000020000080 RSI: 0000000000000013 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000102000004 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000004c6 R14: 00000000006fa330 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:1/22: #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000baaeac49 ((wq_completion)"writeback"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000f7baba02 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 #2: 00000000aa6fdcf6 (&type->s_umount_key#35){++++}, at: trylock_super+0x22/0x110 fs/super.c:395 2 locks held by khungtaskd/888: #0: 00000000acdb9d97 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000acdb9d97 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 000000007ae993e3 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 1 lock held by rsyslogd/4396: #0: 0000000059e4631e (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 2 locks held by getty/4486: #0: 000000003f177bf9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000acb0999 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4487: #0: 0000000086050bb9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000007315cece (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4488: #0: 000000004366016a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e6149a35 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4489: #0: 000000004f6d6246 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000015c0a3a6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4490: #0: 00000000f057b5a0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000007d4a10cb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4491: #0: 00000000817bb246 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000d152ca19 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4492: #0: 00000000f3f9ef5f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000908c6e78 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by blkid/20567: #0: 000000005fadd672 (&bdev->bd_mutex){+.+.}, at: blkdev_put+0x34/0x540 fs/block_dev.c:1810 1 lock held by syz-executor7/21889: #0: 000000005fadd672 (&bdev->bd_mutex){+.+.}, at: blkdev_put+0x34/0x540 fs/block_dev.c:1810 1 lock held by syz-executor7/21945: #0: 000000005fadd672 (&bdev->bd_mutex){+.+.}, at: iterate_bdevs+0xce/0x291 fs/block_dev.c:2157 1 lock held by syz-executor7/21949: #0: 000000005fadd672 (&bdev->bd_mutex){+.+.}, at: iterate_bdevs+0xce/0x291 fs/block_dev.c:2157 1 lock held by syz-executor4/21942: #0: 000000005fadd672 (&bdev->bd_mutex){+.+.}, at: iterate_bdevs+0xce/0x291 fs/block_dev.c:2157 1 lock held by syz-executor4/21959: #0: 000000005fadd672 (&bdev->bd_mutex){+.+.}, at: iterate_bdevs+0xce/0x291 fs/block_dev.c:2157 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 888 Comm: khungtaskd Not tainted 4.16.0+ #19 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 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