====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u8:20/9074 is trying to acquire lock: ffffffff90094cc0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:316 [inline] ffffffff90094cc0 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4673 [inline] ffffffff90094cc0 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:5011 [inline] ffffffff90094cc0 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_cache_noprof+0x61/0x600 mm/slub.c:5676 but task is already holding lock: ffffffff90a1a600 (gdp_mutex){+.+.}-{4:4}, at: get_device_parent+0x16f/0x3a0 drivers/base/core.c:3338 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #8 (gdp_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 get_device_parent+0x16f/0x3a0 drivers/base/core.c:3338 device_add+0x2d4/0xb80 drivers/base/core.c:3685 device_create_groups_vargs drivers/base/core.c:4458 [inline] device_create+0x269/0x300 drivers/base/core.c:4497 msr_device_create+0x33/0x50 arch/x86/kernel/msr.c:254 cpuhp_invoke_callback+0x434/0x810 kernel/cpu.c:194 cpuhp_thread_fun+0x362/0x780 kernel/cpu.c:1109 smpboot_thread_fn+0x5f8/0xb30 kernel/smpboot.c:162 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #7 (cpuhp_state-up){+.+.}-{0:0}: cpuhp_lock_acquire kernel/cpu.c:103 [inline] cpuhp_thread_fun+0x127/0x780 kernel/cpu.c:1086 smpboot_thread_fn+0x5f8/0xb30 kernel/smpboot.c:162 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #6 (cpu_hotplug_lock){++++}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read include/linux/percpu-rwsem.h:77 [inline] cpus_read_lock+0x3d/0x160 kernel/cpu.c:490 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 nbd_genl_reconnect_sock_cb+0x69a/0xbb0 drivers/block/nbd.c:1377 nbd_genl_foreach_sock+0x265/0x450 drivers/block/nbd.c:2152 nbd_genl_reconfigure+0xbbb/0x1040 drivers/block/nbd.c:2477 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2584 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x8ef/0xa80 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x7f0/0xb20 net/netlink/af_netlink.c:1920 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800 __sock_sendmsg net/socket.c:818 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2715 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2769 __sys_sendmsg net/socket.c:2801 [inline] __do_sys_sendmsg net/socket.c:2806 [inline] __se_sys_sendmsg net/socket.c:2804 [inline] __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2804 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x373/0xff0 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2131 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xd36/0x1580 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329 blk_mq_run_work_fn+0x167/0x2f0 block/blk-mq.c:2546 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #4 (&cmd->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 nbd_queue_rq+0xc1/0xff0 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2131 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xd36/0x1580 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329 blk_mq_run_work_fn+0x167/0x2f0 block/blk-mq.c:2546 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #3 (set->srcu){.+.+}-{0:0}: srcu_lock_sync include/linux/srcu.h:225 [inline] __synchronize_srcu+0xca/0x2f0 kernel/rcu/srcutree.c:1662 elevator_switch+0x1e8/0x7b0 block/elevator.c:576 elevator_change+0x2fa/0x480 block/elevator.c:681 elevator_set_default+0x375/0x440 block/elevator.c:754 blk_register_queue+0x404/0x4f0 block/blk-sysfs.c:992 __add_disk+0x6b8/0xdb0 block/genhd.c:531 add_disk_fwnode+0x100/0x3a0 block/genhd.c:600 add_disk include/linux/blkdev.h:801 [inline] nbd_dev_add+0x733/0xb60 drivers/block/nbd.c:2026 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2743 do_one_initcall+0x250/0x870 init/main.c:1419 do_initcall_level+0x10a/0x1a0 init/main.c:1481 do_initcalls+0x59/0xa0 init/main.c:1497 kernel_init_freeable+0x29d/0x3e0 init/main.c:1732 kernel_init+0x22/0x1d0 init/main.c:1622 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 elevator_change+0x1af/0x480 block/elevator.c:679 elevator_set_none+0xb5/0x140 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5114 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5159 [inline] blk_mq_update_nr_hw_queues+0x5ef/0x19e0 block/blk-mq.c:5224 nbd_start_device+0x189/0xb30 drivers/block/nbd.c:1530 nbd_genl_connect+0x167d/0x1cd0 drivers/block/nbd.c:2310 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2584 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x8ef/0xa80 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x7f0/0xb20 net/netlink/af_netlink.c:1920 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800 __sock_sendmsg net/socket.c:818 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2715 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2769 __sys_sendmsg net/socket.c:2801 [inline] __do_sys_sendmsg net/socket.c:2806 [inline] __se_sys_sendmsg net/socket.c:2804 [inline] __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2804 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#49){++++}-{0:0}: blk_alloc_queue+0x544/0x690 block/blk-core.c:505 blk_mq_alloc_queue block/blk-mq.c:4439 [inline] __blk_mq_alloc_disk+0x194/0x390 block/blk-mq.c:4486 nbd_dev_add+0x494/0xb60 drivers/block/nbd.c:1996 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2743 do_one_initcall+0x250/0x870 init/main.c:1419 do_initcall_level+0x10a/0x1a0 init/main.c:1481 do_initcalls+0x59/0xa0 init/main.c:1497 kernel_init_freeable+0x29d/0x3e0 init/main.c:1732 kernel_init+0x22/0x1d0 init/main.c:1622 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (fs_reclaim){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __fs_reclaim_acquire mm/page_alloc.c:4360 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4374 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4673 [inline] slab_alloc_node mm/slub.c:5011 [inline] __kmalloc_cache_noprof+0x61/0x600 mm/slub.c:5676 _kmalloc_noprof include/linux/slab.h:991 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] class_dir_create_and_add drivers/base/core.c:3295 [inline] get_device_parent+0x255/0x3a0 drivers/base/core.c:3355 device_add+0x2d4/0xb80 drivers/base/core.c:3685 netdev_register_kobject+0x197/0x350 net/core/net-sysfs.c:2381 register_netdevice+0x17be/0x2280 net/core/dev.c:11703 nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1101 [inline] nsim_create+0xbe3/0x1100 drivers/net/netdevsim/netdev.c:1183 __nsim_dev_port_add+0x7f8/0xcd0 drivers/net/netdevsim/dev.c:1434 nsim_dev_port_add_all+0x37/0xf0 drivers/net/netdevsim/dev.c:1495 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1547 [inline] nsim_dev_reload_up+0x4dd/0x880 drivers/net/netdevsim/dev.c:983 devlink_reload+0x40b/0x7f0 net/devlink/dev.c:475 devlink_pernet_pre_exit+0x1d9/0x560 net/devlink/core.c:584 ops_pre_exit_list net/core/net_namespace.c:161 [inline] ops_undo_list+0x17d/0x8f0 net/core/net_namespace.c:235 cleanup_net+0x572/0x810 net/core/net_namespace.c:706 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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: fs_reclaim --> cpuhp_state-up --> gdp_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(gdp_mutex); lock(cpuhp_state-up); lock(gdp_mutex); lock(fs_reclaim); *** DEADLOCK *** locks held by kworker/u8:20/9074: 7, last CPU#1: #0: ffff88801cec6148 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801cec6148 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801cec6148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88801cec6148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90007037c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90007037c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90007037c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90007037c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffffffff9147d628 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:677 #3: ffff888023fa8128 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1109 [inline] #3: ffff888023fa8128 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:124 [inline] #3: ffff888023fa8128 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x122/0x560 net/devlink/core.c:581 #4: ffff888023faf258 (&devlink->lock_key#5){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:314 [inline] #4: ffff888023faf258 (&devlink->lock_key#5){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:125 [inline] #4: ffff888023faf258 (&devlink->lock_key#5){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x138/0x560 net/devlink/core.c:581 #5: ffffffff9148c2e0 (rtnl_mutex){+.+.}-{4:4}, at: nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1089 [inline] #5: ffffffff9148c2e0 (rtnl_mutex){+.+.}-{4:4}, at: nsim_create+0x885/0x1100 drivers/net/netdevsim/netdev.c:1183 #6: ffffffff90a1a600 (gdp_mutex){+.+.}-{4:4}, at: get_device_parent+0x16f/0x3a0 drivers/base/core.c:3338 stack backtrace: CPU: 1 UID: 0 PID: 9074 Comm: kworker/u8:20 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026 Workqueue: netns cleanup_net Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219 check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __fs_reclaim_acquire mm/page_alloc.c:4360 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4374 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4673 [inline] slab_alloc_node mm/slub.c:5011 [inline] __kmalloc_cache_noprof+0x61/0x600 mm/slub.c:5676 _kmalloc_noprof include/linux/slab.h:991 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] class_dir_create_and_add drivers/base/core.c:3295 [inline] get_device_parent+0x255/0x3a0 drivers/base/core.c:3355 device_add+0x2d4/0xb80 drivers/base/core.c:3685 netdev_register_kobject+0x197/0x350 net/core/net-sysfs.c:2381 register_netdevice+0x17be/0x2280 net/core/dev.c:11703 nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1101 [inline] nsim_create+0xbe3/0x1100 drivers/net/netdevsim/netdev.c:1183 __nsim_dev_port_add+0x7f8/0xcd0 drivers/net/netdevsim/dev.c:1434 nsim_dev_port_add_all+0x37/0xf0 drivers/net/netdevsim/dev.c:1495 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1547 [inline] nsim_dev_reload_up+0x4dd/0x880 drivers/net/netdevsim/dev.c:983 devlink_reload+0x40b/0x7f0 net/devlink/dev.c:475 devlink_pernet_pre_exit+0x1d9/0x560 net/devlink/core.c:584 ops_pre_exit_list net/core/net_namespace.c:161 [inline] ops_undo_list+0x17d/0x8f0 net/core/net_namespace.c:235 cleanup_net+0x572/0x810 net/core/net_namespace.c:706 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 bond12 (unregistering): (slave xfrm0): Releasing backup interface xfrm0 (unregistering): left promiscuous mode bond1 (unregistering): (slave erspan1): Releasing active interface bond16 (unregistering): (slave gretap2): Releasing active interface bond14 (unregistering): (slave gretap1): Releasing active interface bond0 (unregistering): (slave geneve2): Releasing active interface .` (unregistering): (slave 30): Releasing backup interface .` (unregistering): (slave bond_slave_1): Releasing backup interface .` (unregistering): Released all slaves bond1 (unregistering): Released all slaves bond0 (unregistering): Released all slaves bond2 (unregistering): Released all slaves bond3 (unregistering): Released all slaves bond4 (unregistering): Released all slaves bond5 (unregistering): Released all slaves bond6 (unregistering): Released all slaves bond7 (unregistering): Released all slaves bond8 (unregistering): Released all slaves bond9 (unregistering): Released all slaves bond10 (unregistering): (slave veth0_to_bond): Releasing backup interface bond10 (unregistering): Released all slaves bond11 (unregistering): (slave lo): Releasing backup interface bond11 (unregistering): (slave lo): last VLAN challenged slave left bond - VLAN blocking is removed bond11 (unregistering): Released all slaves bond12 (unregistering): Released all slaves bond13 (unregistering): Released all slaves bond14 (unregistering): Released all slaves bond15 (unregistering): Released all slaves bond16 (unregistering): Released all slaves batman_adv: batadv0: Interface deactivated: batadv_slave_0 batman_adv: batadv0: Removing interface: batadv_slave_0 batman_adv: batadv0: Interface deactivated: batadv_slave_1 batman_adv: batadv0: Removing interface: batadv_slave_1 veth1_macvtap: left promiscuous mode veth0_macvtap: left promiscuous mode veth0_vlan: left promiscuous mode IPVS: stop unused estimator thread 0...