unregister_netdevice: waiting for lo to become free. Usage count = 3 unregister_netdevice: waiting for lo to become free. Usage count = 3 unregister_netdevice: waiting for lo to become free. Usage count = 3 unregister_netdevice: waiting for lo to become free. Usage count = 3 unregister_netdevice: waiting for lo to become free. Usage count = 3 INFO: task syz-executor6:22546 blocked for more than 120 seconds. Not tainted 4.16.0-rc7+ #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D24704 22546 4457 0x00000004 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 mm/filemap.c:1099 [inline] __lock_page+0x574/0x720 mm/filemap.c:1272 lock_page include/linux/pagemap.h:483 [inline] pagecache_get_page+0x674/0xba0 mm/filemap.c:1553 find_lock_page include/linux/pagemap.h:297 [inline] truncate_inode_pages_range+0xc37/0x1fe0 mm/truncate.c:396 blkdev_fallocate+0x1ff/0x3b0 fs/block_dev.c:2006 vfs_fallocate+0x33c/0x6f0 fs/open.c:319 SYSC_fallocate fs/open.c:342 [inline] SyS_fallocate+0x53/0x90 fs/open.c:336 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x454879 RSP: 002b:00007f1c38894c68 EFLAGS: 00000246 ORIG_RAX: 000000000000011d RAX: ffffffffffffffda RBX: 00007f1c388956d4 RCX: 0000000000454879 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 000200007fffffff R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000007d R14: 00000000006f2c58 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/0:0/3: #0: ((wq_completion)"events"){+.+.}, at: [<000000003c4e1938>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"events"){+.+.}, at: [<000000003c4e1938>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"events"){+.+.}, at: [<000000003c4e1938>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"events"){+.+.}, at: [<000000003c4e1938>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: (slab_caches_to_rcu_destroy_work){+.+.}, at: [<0000000031e39415>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (slab_mutex){+.+.}, at: [<000000005b0f224a>] slab_caches_to_rcu_destroy_workfn+0x25/0xc0 mm/slab_common.c:556 2 locks held by khungtaskd/868: #0: (rcu_read_lock){....}, at: [<000000000efc0ad8>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000000efc0ad8>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000c03ad12d>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 1 lock held by rsyslogd/4287: #0: (&f->f_pos_lock){+.+.}, at: [<00000000a6a50806>] __fdget_pos+0x12b/0x190 fs/file.c:765 2 locks held by getty/4377: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4378: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4379: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 unregister_netdevice: waiting for lo to become free. Usage count = 3 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4380: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4381: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4382: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4383: #0: (&tty->ldisc_sem){++++}, at: [<00000000f2279e20>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000279f326a>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:8/15833: #0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000003c4e1938>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000003c4e1938>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000003c4e1938>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000003c4e1938>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: (net_cleanup_work){+.+.}, at: [<0000000031e39415>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (net_mutex){+.+.}, at: [<000000002eee2c2e>] cleanup_net+0x242/0xcb0 net/core/net_namespace.c:484 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 868 Comm: khungtaskd Not tainted 4.16.0-rc7+ #3 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 8 Comm: rcu_sched Not tainted 4.16.0-rc7+ #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:prepare_to_swait+0x4d/0x4f0 kernel/sched/swait.c:78 RSP: 0018:ffff8801d9af7658 EFLAGS: 00000282 RAX: ffffed003b35eecf RBX: 1ffff1003b35eecf RCX: ffffffff866e0600 RDX: 0000000000000402 RSI: ffff8801d9af7e98 RDI: ffffffff87b48ee0 RBP: ffff8801d9af7780 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d9af7758 R13: ffff8801d9af7e98 R14: 0000000000000402 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000007a22006 CR4: 00000000001606f0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: prepare_to_swait_event+0x45/0xc0 kernel/sched/swait.c:93 rcu_gp_kthread+0x8fa/0x18e0 kernel/rcu/tree.c:2230 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 Code: 63 f2 4c 8d 65 d8 48 c1 eb 03 48 81 ec 00 01 00 00 48 c7 85 f8 fe ff ff b3 8a b5 41 4a 8d 04 3b 48 c7 85 00 ff ff ff 38 bc 74 87 <48> c7 85 08 ff ff ff 00 56 55 81 c7 00 f1 f1 f1 f1 c7 40 04 00