block nbd0: shutting down sockets block nbd0: Receive control failed (result -107) block nbd0: shutting down sockets block nbd0: Receive control failed (result -107) ====================================================== WARNING: possible circular locking dependency detected 4.19.89-syzkaller #0 Not tainted ------------------------------------------------------ kworker/u5:0/1204 is trying to acquire lock: 00000000bded6ee3 (&nbd->config_lock){+.+.}, at: refcount_dec_and_mutex_lock lib/refcount.c:311 [inline] 00000000bded6ee3 (&nbd->config_lock){+.+.}, at: refcount_dec_and_mutex_lock+0x52/0x80 lib/refcount.c:306 but task is already holding lock: 00000000d3fb2208 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8b4/0x1750 kernel/workqueue.c:2128 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((work_completion)(&args->work)){+.+.}: process_one_work+0x90f/0x1750 kernel/workqueue.c:2129 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 -> #1 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}: flush_workqueue+0x126/0x14b0 kernel/workqueue.c:2655 drain_workqueue+0x1b4/0x470 kernel/workqueue.c:2820 destroy_workqueue+0x21/0x6b0 kernel/workqueue.c:4158 nbd_config_put+0x3cf/0x860 drivers/block/nbd.c:1161 nbd_release+0xf6/0x140 drivers/block/nbd.c:1436 __blkdev_put+0x4d1/0x810 fs/block_dev.c:1804 blkdev_put+0x98/0x560 fs/block_dev.c:1866 blkdev_close+0x8b/0xb0 fs/block_dev.c:1873 __fput+0x2dd/0x8b0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&nbd->config_lock){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1300 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 refcount_dec_and_mutex_lock lib/refcount.c:311 [inline] refcount_dec_and_mutex_lock+0x52/0x80 lib/refcount.c:306 nbd_config_put+0x31/0x860 drivers/block/nbd.c:1139 recv_work+0x19b/0x200 drivers/block/nbd.c:745 process_one_work+0x989/0x1750 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 other info that might help us debug this: Chain exists of: &nbd->config_lock --> (wq_completion)"knbd%d-recv"nbd->index --> (work_completion)(&args->work) Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&args->work)); lock((wq_completion)"knbd%d-recv"nbd->index); lock((work_completion)(&args->work)); lock(&nbd->config_lock); *** DEADLOCK *** 2 locks held by kworker/u5:0/1204: #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline] #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000b1fdfef6 ((wq_completion)"knbd%d-recv"nbd->index){+.+.}, at: process_one_work+0x87e/0x1750 kernel/workqueue.c:2124 #1: 00000000d3fb2208 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8b4/0x1750 kernel/workqueue.c:2128 stack backtrace: CPU: 1 PID: 1204 Comm: kworker/u5:0 Not tainted 4.19.89-syzkaller #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:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x2e19/0x49c0 kernel/locking/lockdep.c:3411 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1300 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 refcount_dec_and_mutex_lock lib/refcount.c:311 [inline] refcount_dec_and_mutex_lock+0x52/0x80 lib/refcount.c:306 nbd_config_put+0x31/0x860 drivers/block/nbd.c:1139 recv_work+0x19b/0x200 drivers/block/nbd.c:745 process_one_work+0x989/0x1750 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 block nbd0: shutting down sockets