unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 INFO: task syz-executor0:19817 blocked for more than 120 seconds. Not tainted 4.9.89-g960923f #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D28536 19817 3866 0x20020004 ffff8801adba3000 0000000000000000 ffff8801c1d50a80 ffffffff84429880 ffff8801db221b98 ffff8801d79df960 ffffffff838a6c0b 0000000041b58ab3 ffffffff84194320 00ffffff8123c550 ffff8801db222468 ffff8801db222490 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3551 [] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768 [] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5173 [] io_schedule include/linux/sched.h:460 [inline] [] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582 [] __wait_on_bit+0x57/0x120 kernel/sched/wait.c:383 [] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802 [] wait_on_page_writeback include/linux/pagemap.h:526 [inline] [] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453 [] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:483 [] filemap_write_and_wait_range+0x74/0xb0 mm/filemap.c:584 [] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369 [] vfs_fsync_range+0x10a/0x250 fs/sync.c:195 [] vfs_fsync fs/sync.c:209 [inline] [] do_fsync+0x42/0xb0 fs/sync.c:219 [] SYSC_fsync fs/sync.c:228 [inline] [] SyS_fsync+0x16/0x20 fs/sync.c:226 [] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline] [] do_fast_syscall_32+0x2f5/0x870 arch/x86/entry/common.c:387 [] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 Showing all locks held in the system: 2 locks held by khungtaskd/516: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x125/0xa70 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336 1 lock held by rsyslogd/3655: #0: (&f->f_pos_lock){+.+.+.}, at: [] __fdget_pos+0x9f/0xc0 fs/file.c:781 2 locks held by getty/3784: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133 3 locks held by kworker/u4:11/17131: #0: ("writeback"){++++.+}, at: [] work_static include/linux/workqueue.h:186 [inline] #0: ("writeback"){++++.+}, at: [] set_work_data kernel/workqueue.c:617 [inline] #0: ("writeback"){++++.+}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: ("writeback"){++++.+}, at: [] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085 #1: ((&(&wb->dwork)->work)){+.+.+.}, at: [] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089 #2: (&type->s_umount_key#22){.+.+..}, at: [] trylock_super+0x20/0x100 fs/super.c:393 3 locks held by kworker/u4:14/17148: #0: ("%s""netns"){.+.+.+}, at: [] work_static include/linux/workqueue.h:186 [inline] #0: ("%s""netns"){.+.+.+}, at: [] set_work_data kernel/workqueue.c:617 [inline] #0: ("%s""netns"){.+.+.+}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: ("%s""netns"){.+.+.+}, at: [] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085 #1: (net_cleanup_work){+.+.+.}, at: [] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089 #2: (net_mutex){+.+.+.}, at: [] cleanup_net+0x13f/0x610 net/core/net_namespace.c:420 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 516 Comm: khungtaskd Not tainted 4.9.89-g960923f #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d8787d00 ffffffff81d96069 0000000000000000 0000000000000000 0000000000000000 0000000000000001 ffffffff810bb690 ffff8801d8787d38 ffffffff81da118d 0000000000000000 0000000000000000 ffff8801d8256418 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6f0/0xa70 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff838b6756