block nbd3: Receive control failed (result -22) ====================================================== WARNING: possible circular locking dependency detected 5.3.0-next-20190920 #0 Not tainted ------------------------------------------------------ kworker/u5:0/1524 is trying to acquire lock: ffff8880a3030978 (&nbd->config_lock){+.+.}, at: refcount_dec_and_mutex_lock lib/refcount.c:319 [inline] ffff8880a3030978 (&nbd->config_lock){+.+.}, at: refcount_dec_and_mutex_lock+0x56/0x90 lib/refcount.c:314 but task is already holding lock: ffff8880a63ffdc0 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((work_completion)(&args->work)){+.+.}: process_one_work+0x91c/0x1740 kernel/workqueue.c:2245 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 -> #1 ((wq_completion)knbd0-recv){+.+.}: flush_workqueue+0x126/0x14c0 kernel/workqueue.c:2774 drain_workqueue+0x1b4/0x470 kernel/workqueue.c:2939 destroy_workqueue+0x74/0x750 kernel/workqueue.c:4335 nbd_config_put+0x3dd/0x870 drivers/block/nbd.c:1181 nbd_release+0x103/0x150 drivers/block/nbd.c:1460 __blkdev_put+0x4d1/0x810 fs/block_dev.c:1867 blkdev_put+0x98/0x560 fs/block_dev.c:1929 blkdev_close+0x8b/0xb0 fs/block_dev.c:1936 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x904/0x2e60 kernel/exit.c:879 do_group_exit+0x135/0x360 kernel/exit.c:983 __do_sys_exit_group kernel/exit.c:994 [inline] __se_sys_exit_group kernel/exit.c:992 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:992 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&nbd->config_lock){+.+.}: check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 refcount_dec_and_mutex_lock lib/refcount.c:319 [inline] refcount_dec_and_mutex_lock+0x56/0x90 lib/refcount.c:314 nbd_config_put+0x31/0x870 drivers/block/nbd.c:1159 recv_work+0x19b/0x200 drivers/block/nbd.c:787 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 other info that might help us debug this: Chain exists of: &nbd->config_lock --> (wq_completion)knbd0-recv --> (work_completion)(&args->work) Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&args->work)); lock((wq_completion)knbd0-recv); lock((work_completion)(&args->work)); lock(&nbd->config_lock); *** DEADLOCK *** 2 locks held by kworker/u5:0/1524: #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline] #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline] #0: ffff8880948d3d28 ((wq_completion)knbd3-recv){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2240 #1: ffff8880a63ffdc0 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244 stack backtrace: CPU: 1 PID: 1524 Comm: kworker/u5:0 Not tainted 5.3.0-next-20190920 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: knbd3-recv recv_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809 check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 refcount_dec_and_mutex_lock lib/refcount.c:319 [inline] refcount_dec_and_mutex_lock+0x56/0x90 lib/refcount.c:314 nbd_config_put+0x31/0x870 drivers/block/nbd.c:1159 recv_work+0x19b/0x200 drivers/block/nbd.c:787 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 block nbd3: shutting down sockets