====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.5.3277/20312 is trying to acquire lock: ffff88801c6bfa10 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: __kernfs_remove+0x183/0xb80 fs/kernfs/dir.c:1559 but task is already holding lock: ffff88801c6bf980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x51/0x120 fs/kernfs/dir.c:1793 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #10 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1625 kernfs_add_one+0x38/0x850 fs/kernfs/dir.c:826 kernfs_create_dir_ns+0xfc/0x1a0 fs/kernfs/dir.c:1131 internal_create_group+0x36f/0xf40 fs/sysfs/group.c:176 cpuhp_invoke_callback+0x3ab/0x9a0 kernel/cpu.c:194 cpuhp_issue_call+0x1b8/0x970 kernel/cpu.c:2354 __cpuhp_setup_state_cpuslocked+0x431/0x880 kernel/cpu.c:2507 __cpuhp_setup_state+0xf4/0x300 kernel/cpu.c:2536 do_one_initcall+0x121/0x750 init/main.c:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703 kernel_init+0x1f/0x1e0 init/main.c:1593 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #9 (cpuhp_state_mutex){+.+.}-{4:4}: -> #8 (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+0x42/0x170 kernel/cpu.c:490 static_key_disable+0x12/0x20 kernel/jump_label.c:247 __inet_hash_connect+0x143e/0x2000 net/ipv4/inet_hashtables.c:1083 tcp_v4_connect+0xeb3/0x1b40 net/ipv4/tcp_ipv4.c:306 __inet_stream_connect+0x208/0xfa0 net/ipv4/af_inet.c:684 inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:755 __sys_connect_file+0x141/0x1a0 net/socket.c:2148 __sys_connect+0x141/0x170 net/socket.c:2167 __do_sys_connect net/socket.c:2173 [inline] __se_sys_connect net/socket.c:2170 [inline] __x64_sys_connect+0x72/0xb0 net/socket.c:2170 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #7 (sk_lock-AF_INET){+.+.}-{0:0}: lock_sock_nested+0x41/0xf0 net/core/sock.c:3783 lock_sock include/net/sock.h:1713 [inline] inet_shutdown+0x67/0x410 net/ipv4/af_inet.c:915 nbd_mark_nsock_dead+0xae/0x5c0 drivers/block/nbd.c:318 recv_work+0x5fb/0x8c0 drivers/block/nbd.c:1021 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302 process_scheduled_works kernel/workqueue.c:3385 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #6 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0x422/0x1e70 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+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753 submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] submit_bh_wbc+0x681/0x890 fs/buffer.c:2730 submit_bh fs/buffer.c:2735 [inline] block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2351 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107 read_mapping_folio include/linux/pagemap.h:1017 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:724 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695 blkdev_get_whole+0x187/0x290 block/bdev.c:756 bdev_open+0x2c7/0xe40 block/bdev.c:965 blkdev_open+0x34e/0x4f0 block/fops.c:697 do_dentry_open+0x6d8/0x1660 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1079 do_open fs/namei.c:4699 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4858 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&cmd->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0x422/0x1e70 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+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753 submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] submit_bh_wbc+0x681/0x890 fs/buffer.c:2730 submit_bh fs/buffer.c:2735 [inline] block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2351 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107 read_mapping_folio include/linux/pagemap.h:1017 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:724 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695 blkdev_get_whole+0x187/0x290 block/bdev.c:756 bdev_open+0x2c7/0xe40 block/bdev.c:965 blkdev_open+0x34e/0x4f0 block/fops.c:697 do_dentry_open+0x6d8/0x1660 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1079 do_open fs/namei.c:4699 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4858 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (set->srcu){.+.+}-{0:0}: srcu_lock_sync include/linux/srcu.h:199 [inline] __synchronize_srcu+0xa2/0x300 kernel/rcu/srcutree.c:1481 blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline] blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline] blk_mq_quiesce_queue block/blk-mq.c:304 [inline] blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299 elevator_switch+0x17b/0x7e0 block/elevator.c:576 elevator_change+0x352/0x530 block/elevator.c:681 elevator_set_default+0x29e/0x360 block/elevator.c:754 blk_register_queue+0x48e/0x630 block/blk-sysfs.c:987 __add_disk+0x73f/0xe40 block/genhd.c:528 add_disk_fwnode+0x118/0x5c0 block/genhd.c:597 add_disk include/linux/blkdev.h:794 [inline] nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:1984 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x121/0x750 init/main.c:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703 kernel_init+0x1f/0x1e0 init/main.c:1593 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #3 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 elevator_change+0x1bc/0x530 block/elevator.c:679 elevator_set_none+0x92/0xf0 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5131 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5176 [inline] blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5241 nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1489 nbd_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x159/0x420 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+0x585/0x850 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752 __sys_sendmsg+0x170/0x220 net/socket.c:2784 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&q->q_usage_counter(io)#49){++++}-{0:0}: blk_alloc_queue+0x610/0x790 block/blk-core.c:461 blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4450 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4497 nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x121/0x750 init/main.c:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703 kernel_init+0x1f/0x1e0 init/main.c:1593 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4325 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4339 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] kmem_cache_alloc_noprof+0x4c/0x6e0 mm/slub.c:4905 __kernfs_iattrs+0x124/0x3e0 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:59 [inline] __kernfs_setattr+0x4d/0x3c0 fs/kernfs/inode.c:72 kernfs_iop_setattr+0xda/0x130 fs/kernfs/inode.c:126 notify_change+0xb25/0x1330 fs/attr.c:556 do_truncate+0x1df/0x240 fs/open.c:68 handle_truncate fs/namei.c:4307 [inline] do_open fs/namei.c:4703 [inline] path_openat+0x2a55/0x31a0 fs/namei.c:4858 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&root->kernfs_iattr_rwsem){++++}-{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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1625 __kernfs_remove+0x183/0xb80 fs/kernfs/dir.c:1559 kernfs_remove_by_name_ns+0x7c/0x120 fs/kernfs/dir.c:1798 driver_sysfs_remove drivers/base/dd.c:524 [inline] __device_release_driver drivers/base/dd.c:1346 [inline] device_release_driver_internal+0x418/0x620 drivers/base/dd.c:1375 usb_driver_release_interface+0x10e/0x190 drivers/usb/core/driver.c:640 proc_disconnect_claim+0x21b/0x390 drivers/usb/core/devio.c:2491 usbdev_do_ioctl drivers/usb/core/devio.c:2782 [inline] usbdev_ioctl+0xbf5/0x3aa0 drivers/usb/core/devio.c:2826 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/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: &root->kernfs_iattr_rwsem --> cpuhp_state_mutex --> &root->kernfs_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&root->kernfs_rwsem); lock(cpuhp_state_mutex); lock(&root->kernfs_rwsem); lock(&root->kernfs_iattr_rwsem); *** DEADLOCK *** 4 locks held by syz.5.3277/20312: #0: ffff88802b8601d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline] #0: ffff88802b8601d8 (&dev->mutex){....}-{4:4}, at: usbdev_do_ioctl drivers/usb/core/devio.c:2610 [inline] #0: ffff88802b8601d8 (&dev->mutex){....}-{4:4}, at: usbdev_ioctl+0x1a7/0x3aa0 drivers/usb/core/devio.c:2826 #1: ffff88802b9231a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline] #1: ffff88802b9231a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1174 [inline] #1: ffff88802b9231a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1372 #2: ffff88801c6bfaa0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x49/0x120 fs/kernfs/dir.c:1792 #3: ffff88801c6bf980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x51/0x120 fs/kernfs/dir.c:1793 stack backtrace: CPU: 1 UID: 0 PID: 20312 Comm: syz.5.3277 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1625 __kernfs_remove+0x183/0xb80 fs/kernfs/dir.c:1559 kernfs_remove_by_name_ns+0x7c/0x120 fs/kernfs/dir.c:1798 driver_sysfs_remove drivers/base/dd.c:524 [inline] __device_release_driver drivers/base/dd.c:1346 [inline] device_release_driver_internal+0x418/0x620 drivers/base/dd.c:1375 usb_driver_release_interface+0x10e/0x190 drivers/usb/core/driver.c:640 proc_disconnect_claim+0x21b/0x390 drivers/usb/core/devio.c:2491 usbdev_do_ioctl drivers/usb/core/devio.c:2782 [inline] usbdev_ioctl+0xbf5/0x3aa0 drivers/usb/core/devio.c:2826 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9958d9c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9959c27028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f9959016180 RCX: 00007f9958d9c819 RDX: 0000200000000140 RSI: 000000008108551b RDI: 0000000000000005 RBP: 00007f9958e32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9959016218 R14: 00007f9959016180 R15: 00007ffe7d788d68