====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 Not tainted ------------------------------------------------------ syz.2.3085/11799 is trying to acquire lock: ffff000014a73188 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x44/0x8e0 block/blk-mq.c:5041 but task is already holding lock: ffff000014a73230 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_genl_connect+0x450/0x14c4 drivers/block/nbd.c:2111 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&nbd->config_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x144/0x9d8 kernel/locking/mutex.c:747 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:799 refcount_dec_and_mutex_lock+0x44/0xbc lib/refcount.c:118 nbd_config_put+0x28/0x5b0 drivers/block/nbd.c:1423 nbd_release+0x7c/0x128 drivers/block/nbd.c:1735 blkdev_put_whole+0x98/0xf0 block/bdev.c:721 bdev_release+0x2a4/0x510 block/bdev.c:1144 blkdev_release+0x14/0x24 block/fops.c:684 __fput+0x2c8/0x954 fs/file_table.c:465 fput_close_sync+0xdc/0x230 fs/file_table.c:570 __do_sys_close fs/open.c:1589 [inline] __se_sys_close fs/open.c:1574 [inline] __arm64_sys_close+0x6c/0xbc fs/open.c:1574 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x50/0x198 arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x10c/0x138 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #1 (&disk->open_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x144/0x9d8 kernel/locking/mutex.c:747 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:799 __del_gendisk+0x104/0x820 block/genhd.c:710 del_gendisk+0x110/0x1b0 block/genhd.c:823 nbd_dev_remove+0x44/0xe4 drivers/block/nbd.c:268 nbd_dev_remove_work+0x14/0x20 drivers/block/nbd.c:284 process_one_work+0x7cc/0x18d4 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x734/0xb84 kernel/workqueue.c:3402 kthread+0x348/0x5fc kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 -> #0 (&set->update_nr_hwq_lock){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1638/0x2380 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x310/0x38c kernel/locking/lockdep.c:5828 down_write+0xb0/0x1a4 kernel/locking/rwsem.c:1577 blk_mq_update_nr_hw_queues+0x44/0x8e0 block/blk-mq.c:5041 nbd_start_device+0xf8/0x9d0 drivers/block/nbd.c:1476 nbd_genl_connect+0xcb4/0x14c4 drivers/block/nbd.c:2218 genl_family_rcv_msg_doit+0x1b8/0x280 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x3ec/0x5bc net/netlink/genetlink.c:1210 netlink_rcv_skb+0x19c/0x338 net/netlink/af_netlink.c:2552 genl_rcv+0x38/0x50 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x40c/0x6e8 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x644/0xa54 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0xc8/0x168 net/socket.c:727 ____sys_sendmsg+0x504/0x768 net/socket.c:2566 ___sys_sendmsg+0x11c/0x19c net/socket.c:2620 __sys_sendmsg+0x114/0x19c net/socket.c:2652 __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __arm64_sys_sendmsg+0x70/0xa0 net/socket.c:2655 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x50/0x198 arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x10c/0x138 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 other info that might help us debug this: Chain exists of: &set->update_nr_hwq_lock --> &disk->open_mutex --> &nbd->config_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&nbd->config_lock); lock(&disk->open_mutex); lock(&nbd->config_lock); lock(&set->update_nr_hwq_lock); *** DEADLOCK *** 3 locks held by syz.2.3085/11799: #0: ffff8000889050b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:1218 #1: ffff800088904fe8 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffff800088904fe8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffff800088904fe8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffff800088904fe8 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x41c/0x5bc net/netlink/genetlink.c:1209 #2: ffff000014a73230 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_genl_connect+0x450/0x14c4 drivers/block/nbd.c:2111 stack backtrace: CPU: 1 UID: 0 PID: 11799 Comm: syz.2.3085 Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xa4/0xf4 lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x28c/0x370 kernel/locking/lockdep.c:2046 check_noncircular+0x168/0x17c kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1638/0x2380 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x310/0x38c kernel/locking/lockdep.c:5828 down_write+0xb0/0x1a4 kernel/locking/rwsem.c:1577 blk_mq_update_nr_hw_queues+0x44/0x8e0 block/blk-mq.c:5041 nbd_start_device+0xf8/0x9d0 drivers/block/nbd.c:1476 nbd_genl_connect+0xcb4/0x14c4 drivers/block/nbd.c:2218 genl_family_rcv_msg_doit+0x1b8/0x280 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x3ec/0x5bc net/netlink/genetlink.c:1210 netlink_rcv_skb+0x19c/0x338 net/netlink/af_netlink.c:2552 genl_rcv+0x38/0x50 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x40c/0x6e8 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x644/0xa54 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0xc8/0x168 net/socket.c:727 ____sys_sendmsg+0x504/0x768 net/socket.c:2566 ___sys_sendmsg+0x11c/0x19c net/socket.c:2620 __sys_sendmsg+0x114/0x19c net/socket.c:2652 __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __arm64_sys_sendmsg+0x70/0xa0 net/socket.c:2655 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x50/0x198 arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x10c/0x138 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 nbd1: detected capacity change from 0 to 7