block nbd0: Send disconnect failed -32 block nbd0: Send disconnect failed -32 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ udevd/16693 is trying to acquire lock: ffffffff8e882e40 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline] ffffffff8e882e40 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4493 [inline] ffffffff8e882e40 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4846 [inline] ffffffff8e882e40 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_node_noprof+0x4a/0x690 mm/slub.c:4921 but task is already holding lock: ffffffff8ff81f08 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] ffffffff8ff81f08 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast+0x27e/0x560 lib/kobject_uevent.c:410 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #8 (uevent_sock_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] kobject_uevent_net_broadcast+0x27e/0x560 lib/kobject_uevent.c:410 kobject_uevent_env+0x55c/0x9e0 lib/kobject_uevent.c:608 device_add+0x557/0xb70 drivers/base/core.c:3670 device_create_groups_vargs drivers/base/core.c:4371 [inline] device_create+0x269/0x300 drivers/base/core.c:4410 msr_device_create+0x33/0x50 arch/x86/kernel/msr.c:251 cpuhp_invoke_callback+0x445/0x860 kernel/cpu.c:194 cpuhp_thread_fun+0x36b/0x780 kernel/cpu.c:1109 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 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+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 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+0x42/0x160 kernel/cpu.c:490 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 nbd_reconnect_socket drivers/block/nbd.c:1342 [inline] nbd_genl_reconfigure+0x132f/0x1ea0 drivers/block/nbd.c:2431 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 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 net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681 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 -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148 __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+0xdcc/0x1600 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386 blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x28d/0x580 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753 submit_bh fs/buffer.c:2826 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2444 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501 do_read_cache_folio+0x358/0x590 mm/filemap.c:4101 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:723 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694 blkdev_get_whole+0x380/0x510 block/bdev.c:764 bdev_open+0x31e/0xd30 block/bdev.c:973 blkdev_open+0x470/0x610 block/fops.c:697 do_dentry_open+0x785/0x14e0 fs/open.c:949 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4830 do_file_open+0x23e/0x4a0 fs/namei.c:4859 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 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 -> #4 (&cmd->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148 __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+0xdcc/0x1600 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386 blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x28d/0x580 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753 submit_bh fs/buffer.c:2826 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2444 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501 do_read_cache_folio+0x358/0x590 mm/filemap.c:4101 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:723 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694 blkdev_get_whole+0x380/0x510 block/bdev.c:764 bdev_open+0x31e/0xd30 block/bdev.c:973 blkdev_open+0x470/0x610 block/fops.c:697 do_dentry_open+0x785/0x14e0 fs/open.c:949 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4830 do_file_open+0x23e/0x4a0 fs/namei.c:4859 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 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 -> #3 (set->srcu){.+.+}-{0:0}: srcu_lock_sync include/linux/srcu.h:199 [inline] __synchronize_srcu+0xca/0x3e0 kernel/rcu/srcutree.c:1505 elevator_switch+0x1e8/0x7a0 block/elevator.c:576 elevator_change+0x2cc/0x450 block/elevator.c:681 elevator_set_default+0x36c/0x430 block/elevator.c:754 blk_register_queue+0x366/0x430 block/blk-sysfs.c:946 __add_disk+0x677/0xd50 block/genhd.c:528 add_disk_fwnode+0xfb/0x480 block/genhd.c:597 add_disk include/linux/blkdev.h:785 [inline] nbd_dev_add+0x72c/0xb50 drivers/block/nbd.c:1984 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692 do_one_initcall+0x250/0x8d0 init/main.c:1382 do_initcall_level+0x104/0x190 init/main.c:1444 do_initcalls+0x59/0xa0 init/main.c:1460 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692 kernel_init+0x1d/0x1d0 init/main.c:1582 ret_from_fork+0x51e/0xb90 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:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 elevator_change+0x1b3/0x450 block/elevator.c:679 elevator_set_none+0xb5/0x140 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5110 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5155 [inline] blk_mq_update_nr_hw_queues+0x5e7/0x1a60 block/blk-mq.c:5220 nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1489 nbd_genl_connect+0x165b/0x1cf0 drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 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 net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681 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 -> #1 (&q->q_usage_counter(io)#49){++++}-{0:0}: blk_alloc_queue+0x546/0x680 block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4429 [inline] __blk_mq_alloc_disk+0x197/0x390 block/blk-mq.c:4476 nbd_dev_add+0x499/0xb50 drivers/block/nbd.c:1954 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692 do_one_initcall+0x250/0x8d0 init/main.c:1382 do_initcall_level+0x104/0x190 init/main.c:1444 do_initcalls+0x59/0xa0 init/main.c:1460 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692 kernel_init+0x1d/0x1d0 init/main.c:1582 ret_from_fork+0x51e/0xb90 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: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 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4493 [inline] slab_alloc_node mm/slub.c:4846 [inline] kmem_cache_alloc_node_noprof+0x4a/0x690 mm/slub.c:4921 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:289 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x2fa/0x560 lib/kobject_uevent.c:410 kobject_uevent_env+0x55c/0x9e0 lib/kobject_uevent.c:608 nbd_config_put+0x14c/0x580 drivers/block/nbd.c:1440 nbd_release+0xfe/0x140 drivers/block/nbd.c:1756 bdev_release+0x536/0x650 block/bdev.c:-1 blkdev_release+0x15/0x20 block/fops.c:705 __fput+0x44f/0xa70 fs/file_table.c:469 fput_close_sync+0x11f/0x240 fs/file_table.c:574 __do_sys_close fs/open.c:1509 [inline] __se_sys_close fs/open.c:1494 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1494 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 other info that might help us debug this: Chain exists of: fs_reclaim --> cpuhp_state-up --> uevent_sock_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(uevent_sock_mutex); lock(cpuhp_state-up); lock(uevent_sock_mutex); lock(fs_reclaim); *** DEADLOCK *** 3 locks held by udevd/16693: #0: ffff888026dd7358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1a9/0x650 block/bdev.c:1144 #1: ffff888026dc2a78 (&nbd->config_lock){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 #2: ffffffff8ff81f08 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] #2: ffffffff8ff81f08 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast+0x27e/0x560 lib/kobject_uevent.c:410 stack backtrace: CPU: 0 UID: 0 PID: 16693 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4493 [inline] slab_alloc_node mm/slub.c:4846 [inline] kmem_cache_alloc_node_noprof+0x4a/0x690 mm/slub.c:4921 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:289 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x2fa/0x560 lib/kobject_uevent.c:410 kobject_uevent_env+0x55c/0x9e0 lib/kobject_uevent.c:608 nbd_config_put+0x14c/0x580 drivers/block/nbd.c:1440 nbd_release+0xfe/0x140 drivers/block/nbd.c:1756 bdev_release+0x536/0x650 block/bdev.c:-1 blkdev_release+0x15/0x20 block/fops.c:705 __fput+0x44f/0xa70 fs/file_table.c:469 fput_close_sync+0x11f/0x240 fs/file_table.c:574 __do_sys_close fs/open.c:1509 [inline] __se_sys_close fs/open.c:1494 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1494 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 RIP: 0033:0x7f19f44a7407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007ffc41ee9470 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 00007f19f4c51880 RCX: 00007f19f44a7407 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008 RBP: 00007f19f4c516e8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002 R13: 0000560a8a5b1190 R14: 0000000000000008 R15: 0000560a8a5b7ba0 udevd[16693]: inotify_add_watch(7, /dev/nbd0, 10) failed: No such file or directory