IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 block nbd0: Receive control failed (result -22) block nbd0: shutting down sockets ============================================ WARNING: possible recursive locking detected 4.14.151 #0 Not tainted -------------------------------------------- kworker/u5:1/6981 is trying to acquire lock: ("knbd%d-recv"nbd->index){+.+.}, at: [] flush_workqueue+0xda/0x1400 kernel/workqueue.c:2613 but task is already holding lock: ("knbd%d-recv"nbd->index){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] ("knbd%d-recv"nbd->index){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock("knbd%d-recv"nbd->index); lock("knbd%d-recv"nbd->index); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u5:1/6981: #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 #1: ((&args->work)){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 #2: (&nbd->config_lock){+.+.}, at: [] refcount_dec_and_mutex_lock lib/refcount.c:312 [inline] #2: (&nbd->config_lock){+.+.}, at: [] refcount_dec_and_mutex_lock+0x49/0x6c lib/refcount.c:307 stack backtrace: CPU: 0 PID: 6981 Comm: kworker/u5:1 Not tainted 4.14.151 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: knbd0-recv recv_work Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x138/0x197 lib/dump_stack.c:53 print_deadlock_bug kernel/locking/lockdep.c:1796 [inline] check_deadlock kernel/locking/lockdep.c:1843 [inline] validate_chain kernel/locking/lockdep.c:2444 [inline] __lock_acquire.cold+0x2bf/0x8dc kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 flush_workqueue+0x109/0x1400 kernel/workqueue.c:2616 drain_workqueue+0x177/0x3e0 kernel/workqueue.c:2781 destroy_workqueue+0x21/0x620 kernel/workqueue.c:4088 nbd_config_put+0x43c/0x7a0 drivers/block/nbd.c:1124 recv_work+0x18d/0x1f0 drivers/block/nbd.c:724 process_one_work+0x863/0x1600 kernel/workqueue.c:2114 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 kobject: 'batman_adv' (ffff88808df04280): kobject_uevent_env kobject: 'batman_adv' (ffff88808df04280): kobject_uevent_env: filter function caused the event to drop! kobject: 'batman_adv' (ffff88808df04280): kobject_cleanup, parent (null) kobject: 'batman_adv' (ffff88808df04280): calling ktype release kobject: (ffff88808df04280): dynamic_kobj_release kobject: 'batman_adv': free name kobject: 'rx-0' (ffff88809ad0ce50): kobject_cleanup, parent ffff8880a1295048 kobject: 'rx-0' (ffff88809ad0ce50): auto cleanup 'remove' event kobject: 'rx-0' (ffff88809ad0ce50): kobject_uevent_env kobject: 'rx-0' (ffff88809ad0ce50): fill_kobj_path: path = '/devices/virtual/net/syz_tun/queues/rx-0' kobject: 'rx-0' (ffff88809ad0ce50): auto cleanup kobject_del kobject: 'rx-0' (ffff88809ad0ce50): calling ktype release kobject: 'rx-0': free name kobject: 'tx-0' (ffff8880917c5058): kobject_cleanup, parent ffff8880a1295048 kobject: 'tx-0' (ffff8880917c5058): auto cleanup 'remove' event kobject: 'tx-0' (ffff8880917c5058): kobject_uevent_env kobject: 'tx-0' (ffff8880917c5058): fill_kobj_path: path = '/devices/virtual/net/syz_tun/queues/tx-0' kobject: 'tx-0' (ffff8880917c5058): auto cleanup kobject_del kobject: 'tx-0' (ffff8880917c5058): calling ktype release kobject: 'tx-0': free name kobject: 'queues' (ffff8880a1295048): kobject_cleanup, parent (null) kobject: 'queues' (ffff8880a1295048): calling ktype release kobject: 'queues' (ffff8880a1295048): kset_release kobject: 'queues': free name kobject: 'syz_tun' (ffff8880a9490a70): kobject_uevent_env kobject: 'syz_tun' (ffff8880a9490a70): fill_kobj_path: path = '/devices/virtual/net/syz_tun' IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready