INFO: task loop0:10491 blocked for more than 120 seconds. Not tainted 4.15.0-rc9+ #283 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. loop0 D24976 10491 2 0x80000000 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 schedule_timeout+0x1a3/0x230 kernel/time/timer.c:1769 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5030 do_wait_for_common kernel/sched/completion.c:86 [inline] __wait_for_common kernel/sched/completion.c:107 [inline] wait_for_common_io kernel/sched/completion.c:124 [inline] wait_for_completion_io+0x415/0x770 kernel/sched/completion.c:172 submit_bio_wait+0x13f/0x1e0 block/bio.c:947 blkdev_issue_flush+0x226/0x310 block/blk-flush.c:548 blkdev_fsync+0x86/0xb0 fs/block_dev.c:632 vfs_fsync_range+0x110/0x260 fs/sync.c:196 vfs_fsync+0x29/0x30 fs/sync.c:210 lo_req_flush drivers/block/loop.c:444 [inline] do_req_filebacked drivers/block/loop.c:572 [inline] loop_handle_cmd drivers/block/loop.c:1724 [inline] loop_queue_work+0x12a2/0x3900 drivers/block/loop.c:1738 kthread_worker_fn+0x32b/0x980 kernel/kthread.c:642 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:841 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:541 Showing all locks held in the system: 2 locks held by khungtaskd/760: #0: (rcu_read_lock){....}, at: [<00000000409d87a4>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000409d87a4>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<0000000013feb9ff>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 1 lock held by rsyslogd/3529: #0: (&f->f_pos_lock){+.+.}, at: [<000000009fc8c084>] __fdget_pos+0x12b/0x190 fs/file.c:770 2 locks held by getty/3651: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3652: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3653: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3654: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3655: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3656: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3657: #0: (&tty->ldisc_sem){++++}, at: [<0000000020b6bfb1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a897dcb0>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 760 Comm: khungtaskd Not tainted 4.15.0-rc9+ #283 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc9+ #283 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline] RIP: 0010:hlist_empty include/linux/list.h:641 [inline] RIP: 0010:perf_trace_lock+0x1e3/0x900 include/trace/events/lock.h:39 RSP: 0018:ffff8801db307910 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 1ffff1003b660f2a RCX: 0000000000000000 RDX: 0000000000000006 RSI: dffffc0000000000 RDI: ffff8801db307a70 RBP: ffff8801db307ad8 R08: ffffffff8813afc8 R09: ffff8801db307970 R10: ffff8801db307b00 R11: 0000000000000000 R12: ffff8801db307ab0 R13: ffffe8ffffd45a88 R14: ffffffff86b2ae60 R15: ffff8801db307a70 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001969000 CR3: 0000000006a22005 CR4: 00000000001606e0 Call Trace: trace_lock_release include/trace/events/lock.h:58 [inline] lock_release+0x618/0xa40 kernel/locking/lockdep.c:3932 seqcount_lockdep_reader_access include/linux/seqlock.h:82 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] ktime_get+0x144/0x3a0 kernel/time/timekeeping.c:762 tick_nohz_irq_enter kernel/time/tick-sched.c:1148 [inline] tick_irq_enter+0x9e/0x390 kernel/time/tick-sched.c:1169 irq_enter+0xb6/0xd0 kernel/softirq.c:346 scheduler_ipi+0x23d/0x820 kernel/sched/core.c:1793 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:961 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9f77cb0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3eef99 RCX: 0000000000000000 RDX: 1ffffffff0d59190 RSI: 0000000000000001 RDI: ffffffff86ac8c80 RBP: ffff8801d9f77cb0 R08: ffffffff868a6ae8 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9f77d68 R14: ffffffff8725b460 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:355 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:346 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:351 start_secondary+0x40a/0x590 arch/x86/kernel/smpboot.c:268 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: fe 48 c1 ee 03 c6 04 06 00 4c 89 ee 48 c1 ee 03 80 3c 06 00 0f 85 ef 03 00 00 4c 89 ff 48 be 00 00 00 00 00 fc ff df 49 8b 45 00 <48> c1 ef 03 80 3c 37 00 0f 85 8d 03 00 00 49 c1 ef 03 48 be 00