Buffer I/O error on dev loop0, logical block 3, async page read INFO: task syz-executor7:466 blocked for more than 120 seconds. Not tainted 4.14.0-rc8+ #79 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D23216 466 25667 0x20020004 Call Trace: context_switch kernel/sched/core.c:2790 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3366 schedule+0xf5/0x430 kernel/sched/core.c:3425 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3483 __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:2157 sys_sync+0x114/0x1c0 fs/sync.c:116 do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline] do_fast_syscall_32+0x3f2/0xf05 arch/x86/entry/common.c:391 entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 RIP: 0023:0xf7efdc79 RSP: 002b:00000000f76f901c 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: 2 locks held by khungtaskd/662: #0: (rcu_read_lock){....}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.?.+}, at: [] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4544 1 lock held by rsyslogd/2925: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x12b/0x190 fs/file.c:768 2 locks held by getty/3008: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 2 locks held by getty/3009: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 2 locks held by getty/3010: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 2 locks held by getty/3011: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 2 locks held by getty/3012: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 2 locks held by getty/3013: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 2 locks held by getty/14050: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2133 3 locks held by kworker/u4:11/19506: #0: ("writeback"){+.+.}, at: [] __write_once_size include/linux/compiler.h:306 [inline] #0: ("writeback"){+.+.}, at: [] atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ("writeback"){+.+.}, at: [] atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: ("writeback"){+.+.}, at: [] set_work_data kernel/workqueue.c:618 [inline] #0: ("writeback"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline] #0: ("writeback"){+.+.}, at: [] process_one_work+0xadf/0x1bc0 kernel/workqueue.c:2084 #1: ((&(&wb->dwork)->work)){+.+.}, at: [] process_one_work+0xb32/0x1bc0 kernel/workqueue.c:2088 #2: (&type->s_umount_key#31){++++}, at: [] trylock_super+0x20/0x100 fs/super.c:392 1 lock held by blkid/425: #0: (&bdev->bd_mutex){+.+.}, at: [] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1805 1 lock held by syz-executor7/466: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2157 1 lock held by syz-executor7/469: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2157 1 lock held by syz-executor7/481: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2157 1 lock held by syz-executor7/505: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2157 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 662 Comm: khungtaskd Not tainted 4.14.0-rc8+ #79 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+0x35e/0x430 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc8+ #79 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffffffff85c2c340 task.stack: ffffffff85c00000 RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:2359 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:2378 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:2432 [inline] RIP: 0010:__lock_acquire+0x1390/0x3df0 kernel/locking/lockdep.c:3490 RSP: 0018:ffff8801db207850 EFLAGS: 00000092 RAX: 1ffffffff0ce9cd3 RBX: ffffffff85c2cbc0 RCX: 1ffff1003b640f32 RDX: dffffc0000000000 RSI: 00000000c1c6c19b RDI: ffffffff8674e698 RBP: ffff8801db207be0 R08: 1ffff1003b640ee7 R09: 000000000000000e R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000001ef0 R13: e378804bf4a0b5b9 R14: ffffffff8674e688 R15: ffffffff85c2c340 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c42d60f000 CR3: 00000001d3bba000 CR4: 00000000001406f0 Call Trace: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3994 seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] ktime_get+0x12f/0x3a0 kernel/time/timekeeping.c:758 tick_nohz_irq_enter kernel/time/tick-sched.c:1144 [inline] tick_irq_enter+0x9e/0x390 kernel/time/tick-sched.c:1165 irq_enter+0xb6/0xd0 kernel/softirq.c:345 scheduler_ipi+0x8c/0x460 kernel/sched/core.c:1784 smp_reschedule_interrupt+0xf2/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:795 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff85c07d08 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0b80fa4 RCX: 0000000000000000 RDX: 1ffffffff0b98cdc RSI: 0000000000000001 RDI: ffffffff85cc66e0 RBP: ffffffff85c07d08 R08: ffffffff859c5a60 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85cc66d0 R13: ffffffff85c07dc0 R14: 0000000000000000 R15: ffffffff85cc66c0 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:342 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:333 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24e/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351 rest_init+0xed/0xf0 init/main.c:435 start_kernel+0x72e/0x754 init/main.c:710 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xa5 arch/x86/kernel/head_64.S:236 Code: 00 00 49 83 fe 08 0f 84 e1 00 00 00 49 8d 7e 10 48 89 f8 48 c1 e8 03 80 3c 10 00 0f 85 fa 27 00 00 4d 3b 6e 10 0f 84 76 f4 ff ff <48> 8d 8d f0 fd ff ff 48 b8 00 00 00 00 00 fc ff df 48 89 ca 48