unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 INFO: task syz-executor2:20158 blocked for more than 120 seconds. Not tainted 4.16.0-rc4+ #253 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D17592 20158 14236 0xa0020006 Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x8fb/0x1ec0 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 io_schedule+0x1c/0x70 kernel/sched/core.c:5115 wait_on_page_bit_common+0x4b3/0x770 mm/filemap.c:1099 wait_on_page_bit mm/filemap.c:1132 [inline] wait_on_page_writeback include/linux/pagemap.h:546 [inline] __filemap_fdatawait_range+0x282/0x430 mm/filemap.c:533 filemap_fdatawait_range mm/filemap.c:558 [inline] filemap_fdatawait include/linux/fs.h:2590 [inline] filemap_write_and_wait+0x7a/0xd0 mm/filemap.c:624 __sync_blockdev fs/block_dev.c:448 [inline] sync_blockdev.part.30+0x50/0x70 fs/block_dev.c:457 sync_blockdev fs/block_dev.c:444 [inline] __blkdev_put+0x18b/0x760 fs/block_dev.c:1781 blkdev_put+0x85/0x4f0 fs/block_dev.c:1850 blkdev_close+0x8b/0xb0 fs/block_dev.c:1857 __fput+0x327/0x7e0 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9bb/0x1ad0 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x73a/0x16d0 kernel/signal.c:2469 do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x258/0x2f0 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_32_irqs_on arch/x86/entry/common.c:336 [inline] do_fast_syscall_32+0xbe6/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f9fc99 RSP: 002b:00000000f779b09c EFLAGS: 00000286 ORIG_RAX: 00000000000000bb RAX: 0000000000041000 RBX: 0000000000000013 RCX: 0000000000000014 RDX: 00000000200ddff8 RSI: 0000000002000001 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: 3 locks held by kworker/u4:0/5: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000d73c0c76>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000d73c0c76>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000d73c0c76>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000d73c0c76>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000468db8b3>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<000000003e0fe8a7>] trylock_super+0x20/0x100 fs/super.c:395 4 locks held by kworker/u4:1/21: #0: ((wq_completion)"%s""netns"){+.+.}, at: [<00000000d73c0c76>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"%s""netns"){+.+.}, at: [<00000000d73c0c76>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"%s""netns"){+.+.}, at: [<00000000d73c0c76>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"%s""netns"){+.+.}, at: [<00000000d73c0c76>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: (net_cleanup_work){+.+.}, at: [<00000000468db8b3>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (net_mutex){+.+.}, at: [<00000000a57182a6>] cleanup_net+0x242/0xcb0 net/core/net_namespace.c:484 #3: (rcu_sched_state.barrier_mutex){+.+.}, at: [<00000000248bcba2>] _rcu_barrier+0x142/0x750 kernel/rcu/tree.c:3517 2 locks held by khungtaskd/799: #0: (rcu_read_lock){....}, at: [<00000000c24b9194>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000c24b9194>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<000000002fa03de2>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 1 lock held by rsyslogd/3998: #0: (&f->f_pos_lock){+.+.}, at: [<00000000e19cf32f>] __fdget_pos+0x12b/0x190 fs/file.c:765 2 locks held by getty/4120: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4121: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4122: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4123: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4124: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4125: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4126: #0: (&tty->ldisc_sem){++++}, at: [<0000000085b6702c>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c8793e0a>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor2/20158: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000ba243999>] __blkdev_put+0xbc/0x760 fs/block_dev.c:1775 1 lock held by blkid/20193: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000b34f688b>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 799 Comm: khungtaskd Not tainted 4.16.0-rc4+ #253 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+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 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:406 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