====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.1072/10652 is trying to acquire lock: ffffffff8e643960 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:318 [inline] ffffffff8e643960 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4721 [inline] ffffffff8e643960 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:5044 [inline] ffffffff8e643960 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:5425 [inline] ffffffff8e643960 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_noprof+0x9c/0x7f0 mm/slub.c:5438 but task is already holding lock: ffffffff8e3e3dc8 (wq_pool_mutex){+.+.}-{4:4}, at: apply_wqattrs_lock kernel/workqueue.c:5211 [inline] ffffffff8e3e3dc8 (wq_pool_mutex){+.+.}-{4:4}, at: __alloc_workqueue+0x9eb/0x1b70 kernel/workqueue.c:5766 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #8 (wq_pool_mutex){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 apply_wqattrs_lock kernel/workqueue.c:5211 [inline] __alloc_workqueue+0x9eb/0x1b70 kernel/workqueue.c:5766 alloc_workqueue_noprof+0xd4/0x210 kernel/workqueue.c:5818 padata_alloc+0xc1/0x370 kernel/padata.c:970 pcrypt_init_padata+0x27/0x100 crypto/pcrypt.c:328 pcrypt_init+0x60/0xc0 crypto/pcrypt.c:353 do_one_initcall+0x236/0x820 init/main.c:1281 do_initcall_level+0x104/0x190 init/main.c:1343 do_initcalls+0x59/0xa0 init/main.c:1359 kernel_init_freeable+0x334/0x4b0 init/main.c:1591 kernel_init+0x1d/0x1d0 init/main.c:1481 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #7 (cpu_hotplug_lock){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 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:491 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 tcp_md5_do_add+0x21f/0x3a0 net/ipv4/tcp_ipv4.c:1433 tcp_v4_parse_md5_keys+0x412/0x600 net/ipv4/tcp_ipv4.c:1574 do_tcp_setsockopt+0x11dc/0x1f20 net/ipv4/tcp.c:4029 do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2347 __sys_setsockopt net/socket.c:2372 [inline] __do_sys_setsockopt net/socket.c:2378 [inline] __se_sys_setsockopt net/socket.c:2375 [inline] __x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2375 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #6 (sk_lock-AF_INET){+.+.}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 lock_sock_nested+0x48/0x100 net/core/sock.c:3720 lock_sock include/net/sock.h:1676 [inline] inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:905 nbd_mark_nsock_dead+0x2e9/0x560 drivers/block/nbd.c:318 sock_shutdown+0x15e/0x260 drivers/block/nbd.c:411 nbd_clear_sock drivers/block/nbd.c:1424 [inline] nbd_config_put+0x342/0x790 drivers/block/nbd.c:1448 nbd_release+0xfe/0x140 drivers/block/nbd.c:1753 bdev_release+0x536/0x650 block/bdev.c:-1 blkdev_release+0x15/0x20 block/fops.c:702 __fput+0x44c/0xa70 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xec/0x130 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&nsock->tx_lock){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 nbd_handle_cmd drivers/block/nbd.c:1140 [inline] nbd_queue_rq+0x257/0xf10 drivers/block/nbd.c:1204 blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2129 __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+0xda4/0x1570 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:2367 blk_mq_dispatch_list+0xd0c/0xe00 include/linux/spinlock.h:-1 blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2976 __blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1223 blk_finish_plug block/blk-core.c:1250 [inline] __submit_bio+0x2d3/0x5a0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2fb/0xa50 block/blk-core.c:753 submit_bh fs/buffer.c:2829 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2447 filemap_read_folio+0x117/0x380 mm/filemap.c:2426 do_read_cache_folio+0x350/0x590 mm/filemap.c:3991 read_mapping_folio include/linux/pagemap.h:999 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:722 adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360 check_partition block/partitions/core.c:141 [inline] blk_add_partitions block/partitions/core.c:589 [inline] bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693 blkdev_get_whole+0x380/0x510 block/bdev.c:748 bdev_open+0x31e/0xd30 block/bdev.c:957 blkdev_open+0x457/0x600 block/fops.c:694 do_dentry_open+0x953/0x13f0 fs/open.c:965 vfs_open+0x3b/0x340 fs/open.c:1095 do_open fs/namei.c:3895 [inline] path_openat+0x2ee5/0x3830 fs/namei.c:4054 do_filp_open+0x1fa/0x410 fs/namei.c:4081 do_sys_openat2+0x121/0x1c0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&cmd->lock){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 nbd_queue_rq+0xc8/0xf10 drivers/block/nbd.c:1196 blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2129 __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+0xda4/0x1570 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:2367 blk_mq_dispatch_list+0xd0c/0xe00 include/linux/spinlock.h:-1 blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2976 __blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1223 blk_finish_plug block/blk-core.c:1250 [inline] __submit_bio+0x2d3/0x5a0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2fb/0xa50 block/blk-core.c:753 submit_bh fs/buffer.c:2829 [inline] __bread_slow fs/buffer.c:1272 [inline] __bread_gfp+0x216/0x3c0 fs/buffer.c:1518 sb_bread include/linux/buffer_head.h:346 [inline] adfs_probe+0x1cb/0x720 fs/adfs/super.c:276 adfs_fill_super+0x15e/0x5c0 fs/adfs/super.c:354 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691 vfs_get_tree+0x92/0x2b0 fs/super.c:1751 fc_mount fs/namespace.c:1274 [inline] do_new_mount_fc fs/namespace.c:3726 [inline] do_new_mount+0x302/0xa10 fs/namespace.c:3802 do_mount fs/namespace.c:4125 [inline] __do_sys_mount fs/namespace.c:4324 [inline] __se_sys_mount+0x313/0x410 fs/namespace.c:4301 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (set->srcu){.+.+}-{0:0}: lock_sync+0xba/0x160 kernel/locking/lockdep.c:5916 srcu_lock_sync include/linux/srcu.h:173 [inline] __synchronize_srcu+0x96/0x3a0 kernel/rcu/srcutree.c:1429 elevator_switch+0x12b/0x640 block/elevator.c:588 elevator_change+0x315/0x4c0 block/elevator.c:691 elevator_set_default+0x186/0x260 block/elevator.c:767 blk_register_queue+0x34e/0x3f0 block/blk-sysfs.c:942 __add_disk+0x677/0xd50 block/genhd.c:528 add_disk_fwnode+0xfc/0x480 block/genhd.c:597 add_disk include/linux/blkdev.h:775 [inline] nbd_dev_add+0x717/0xae0 drivers/block/nbd.c:1981 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2688 do_one_initcall+0x236/0x820 init/main.c:1281 do_initcall_level+0x104/0x190 init/main.c:1343 do_initcalls+0x59/0xa0 init/main.c:1359 kernel_init_freeable+0x334/0x4b0 init/main.c:1591 kernel_init+0x1d/0x1d0 init/main.c:1481 ret_from_fork+0x4bc/0x870 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}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 elevator_change+0x1e5/0x4c0 block/elevator.c:689 elevator_set_none+0x42/0xb0 block/elevator.c:782 blk_mq_elv_switch_none block/blk-mq.c:5034 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5077 [inline] blk_mq_update_nr_hw_queues+0x598/0x1ab0 block/blk-mq.c:5135 nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1486 nbd_genl_connect+0x135b/0x18f0 drivers/block/nbd.c:2236 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:729 ____sys_sendmsg+0x505/0x830 net/socket.c:2617 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2671 __sys_sendmsg net/socket.c:2703 [inline] __do_sys_sendmsg net/socket.c:2708 [inline] __se_sys_sendmsg net/socket.c:2706 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2706 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#49){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 blk_alloc_queue+0x538/0x620 block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4401 [inline] __blk_mq_alloc_disk+0x15c/0x340 block/blk-mq.c:4448 nbd_dev_add+0x46c/0xae0 drivers/block/nbd.c:1951 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2688 do_one_initcall+0x236/0x820 init/main.c:1281 do_initcall_level+0x104/0x190 init/main.c:1343 do_initcalls+0x59/0xa0 init/main.c:1359 kernel_init_freeable+0x334/0x4b0 init/main.c:1591 kernel_init+0x1d/0x1d0 init/main.c:1481 ret_from_fork+0x4bc/0x870 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4245 [inline] fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4259 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4721 [inline] slab_alloc_node mm/slub.c:5044 [inline] __do_kmalloc_node mm/slub.c:5425 [inline] __kmalloc_noprof+0x9c/0x7f0 mm/slub.c:5438 kmalloc_noprof include/linux/slab.h:960 [inline] kzalloc_noprof include/linux/slab.h:1090 [inline] apply_wqattrs_prepare+0xf6/0xe00 kernel/workqueue.c:5306 apply_workqueue_attrs_locked+0x65/0x240 kernel/workqueue.c:5396 alloc_and_link_pwqs kernel/workqueue.c:5546 [inline] __alloc_workqueue+0x10c5/0x1b70 kernel/workqueue.c:5768 alloc_workqueue_noprof+0xd4/0x210 kernel/workqueue.c:5818 hci_register_dev+0x208/0x890 net/bluetooth/hci_core.c:2604 hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:691 [inline] hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:717 [inline] hci_uart_tty_ioctl+0x828/0xa00 drivers/bluetooth/hci_ldisc.c:771 tty_ioctl+0x9c6/0xde0 drivers/tty/tty_io.c:2801 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 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 --> cpu_hotplug_lock --> wq_pool_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(wq_pool_mutex); lock(cpu_hotplug_lock); lock(wq_pool_mutex); lock(fs_reclaim); *** DEADLOCK *** 2 locks held by syz.1.1072/10652: #0: ffff8880695030a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffffff8e3e3dc8 (wq_pool_mutex){+.+.}-{4:4}, at: apply_wqattrs_lock kernel/workqueue.c:5211 [inline] #1: ffffffff8e3e3dc8 (wq_pool_mutex){+.+.}-{4:4}, at: __alloc_workqueue+0x9eb/0x1b70 kernel/workqueue.c:5766 stack backtrace: CPU: 1 UID: 0 PID: 10652 Comm: syz.1.1072 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4245 [inline] fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4259 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4721 [inline] slab_alloc_node mm/slub.c:5044 [inline] __do_kmalloc_node mm/slub.c:5425 [inline] __kmalloc_noprof+0x9c/0x7f0 mm/slub.c:5438 kmalloc_noprof include/linux/slab.h:960 [inline] kzalloc_noprof include/linux/slab.h:1090 [inline] apply_wqattrs_prepare+0xf6/0xe00 kernel/workqueue.c:5306 apply_workqueue_attrs_locked+0x65/0x240 kernel/workqueue.c:5396 alloc_and_link_pwqs kernel/workqueue.c:5546 [inline] __alloc_workqueue+0x10c5/0x1b70 kernel/workqueue.c:5768 alloc_workqueue_noprof+0xd4/0x210 kernel/workqueue.c:5818 hci_register_dev+0x208/0x890 net/bluetooth/hci_core.c:2604 hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:691 [inline] hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:717 [inline] hci_uart_tty_ioctl+0x828/0xa00 drivers/bluetooth/hci_ldisc.c:771 tty_ioctl+0x9c6/0xde0 drivers/tty/tty_io.c:2801 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0678b8eba9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0679a26038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f0678dd6180 RCX: 00007f0678b8eba9 RDX: 0000000000000000 RSI: 00000000400455c8 RDI: 0000000000000005 RBP: 00007f0678c11e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0678dd6218 R14: 00007f0678dd6180 R15: 00007ffe46ab1d48