block nbd1: Receive control failed (result -32) ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u9:3/5827 is trying to acquire lock: ffff8880275b9a78 (&nbd->config_lock){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 but task is already holding lock: ffffc90003bd7c40 ((work_completion)(&args->work)#3){+.+.}-{0:0}, at: process_one_work+0x87c/0x1650 kernel/workqueue.c:3255 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((work_completion)(&args->work)#3){+.+.}-{0:0}: process_one_work+0x895/0x1650 kernel/workqueue.c:3255 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 ((wq_completion)nbd3-recv){+.+.}-{0:0}: touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:3994 __flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:4036 nbd_disconnect_and_put+0x9e/0x2c0 drivers/block/nbd.c:2264 nbd_genl_disconnect+0x4a9/0x590 drivers/block/nbd.c:2303 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x18f/0x1d0 net/socket.c:737 __sock_sendmsg net/socket.c:752 [inline] ____sys_sendmsg+0x589/0x8c0 net/socket.c:2610 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2664 __sys_sendmsg net/socket.c:2696 [inline] __do_sys_sendmsg net/socket.c:2701 [inline] __se_sys_sendmsg net/socket.c:2699 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2699 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&nbd->config_lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 nbd_config_put+0x2c/0x580 drivers/block/nbd.c:1434 recv_work+0x1cc1/0x1d90 drivers/block/nbd.c:1026 process_one_work+0x949/0x1650 kernel/workqueue.c:3279 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: &nbd->config_lock --> (wq_completion)nbd3-recv --> (work_completion)(&args->work)#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&args->work)#3); lock((wq_completion)nbd3-recv); lock((work_completion)(&args->work)#3); lock(&nbd->config_lock); *** DEADLOCK *** 2 locks held by kworker/u9:3/5827: #0: ffff8880275c9148 ((wq_completion)nbd1-recv){+.+.}-{0:0}, at: process_one_work+0x855/0x1650 kernel/workqueue.c:3254 #1: ffffc90003bd7c40 ((work_completion)(&args->work)#3){+.+.}-{0:0}, at: process_one_work+0x87c/0x1650 kernel/workqueue.c:3255 stack backtrace: CPU: 0 UID: 0 PID: 5827 Comm: kworker/u9:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: nbd1-recv recv_work Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 nbd_config_put+0x2c/0x580 drivers/block/nbd.c:1434 recv_work+0x1cc1/0x1d90 drivers/block/nbd.c:1026 process_one_work+0x949/0x1650 kernel/workqueue.c:3279 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 block nbd1: shutting down sockets