Bluetooth: hci4: link tx timeout
Bluetooth: hci4: killing stalled connection 10:aa:aa:aa:aa:aa
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u9:0/18686 is trying to acquire lock:
ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:316 [inline]
ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4636 [inline]
ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4974 [inline]
ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:5413 [inline]
ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_noprof+0xbc/0x720 mm/slub.c:5439

but task is already holding lock:
ffffffff8f8120c0 (dpm_list_mtx){+.+.}-{4:4}, at: device_move+0x3c/0x720 drivers/base/core.c:4682

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #9 (dpm_list_mtx){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       device_pm_add+0x7d/0x350 drivers/base/power/main.c:156
       device_add+0x4eb/0xb80 drivers/base/core.c:3724
       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+0x565/0xa70 kernel/smpboot.c:160
       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

-> #8 (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+0x565/0xa70 kernel/smpboot.c:160
       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 (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_disable+0x12/0x20 kernel/jump_label.c:247
       __inet_hash_connect+0x258f/0x25a0 net/ipv4/inet_hashtables.c:1081
       tcp_v4_connect+0xcee/0x1950 net/ipv4/tcp_ipv4.c:306
       __inet_stream_connect+0x258/0xe00 net/ipv4/af_inet.c:684
       inet_stream_connect+0x66/0xa0 net/ipv4/af_inet.c:755
       connect_socket net/socket.c:2141 [inline]
       __sys_connect_file net/socket.c:2166 [inline]
       __sys_connect+0x316/0x450 net/socket.c:2183
       __do_sys_connect net/socket.c:2189 [inline]
       __se_sys_connect net/socket.c:2186 [inline]
       __x64_sys_connect+0x7a/0x90 net/socket.c:2186
       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

-> #6 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x41/0x100 net/core/sock.c:3830
       lock_sock include/net/sock.h:1713 [inline]
       inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:913
       nbd_mark_nsock_dead+0x2cb/0x550 drivers/block/nbd.c:319
       recv_work+0x1cee/0x1e10 drivers/block/nbd.c:1030
       process_one_work kernel/workqueue.c:3396 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
       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

-> #5 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 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:2117
       __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+0x16c/0x300 block/blk-mq.c:2532
       process_one_work kernel/workqueue.c:3396 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
       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+0x19d/0x1550 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:2117
       __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+0x16c/0x300 block/blk-mq.c:2532
       process_one_work kernel/workqueue.c:3396 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
       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:210 [inline]
       __synchronize_srcu+0xc9/0x2f0 kernel/rcu/srcutree.c:1462
       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+0x3f3/0x4e0 block/blk-sysfs.c:992
       __add_disk+0x6cb/0xe30 block/genhd.c:524
       add_disk_fwnode+0x100/0x3a0 block/genhd.c:593
       add_disk include/linux/blkdev.h:798 [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:1357
       do_initcall_level+0x10a/0x1a0 init/main.c:1419
       do_initcalls+0x59/0xa0 init/main.c:1435
       kernel_init_freeable+0x29d/0x3e0 init/main.c:1670
       kernel_init+0x22/0x1d0 init/main.c:1560
       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+0x19d/0x1550 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:5102 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5147 [inline]
       blk_mq_update_nr_hw_queues+0x5ef/0x19f0 block/blk-mq.c:5212
       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:2556
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
       netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
       netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1345
       netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
       sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
       __sock_sendmsg net/socket.c:815 [inline]
       ____sys_sendmsg+0x54e/0x850 net/socket.c:2713
       ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
       __sys_sendmsg net/socket.c:2799 [inline]
       __do_sys_sendmsg net/socket.c:2804 [inline]
       __se_sys_sendmsg net/socket.c:2802 [inline]
       __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2802
       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:504
       blk_mq_alloc_queue block/blk-mq.c:4420 [inline]
       __blk_mq_alloc_disk+0x194/0x390 block/blk-mq.c:4467
       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:1357
       do_initcall_level+0x10a/0x1a0 init/main.c:1419
       do_initcalls+0x59/0xa0 init/main.c:1435
       kernel_init_freeable+0x29d/0x3e0 init/main.c:1670
       kernel_init+0x22/0x1d0 init/main.c:1560
       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:3181 [inline]
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
       __fs_reclaim_acquire mm/page_alloc.c:4375 [inline]
       fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4389
       might_alloc include/linux/sched/mm.h:316 [inline]
       slab_pre_alloc_hook mm/slub.c:4636 [inline]
       slab_alloc_node mm/slub.c:4974 [inline]
       __do_kmalloc_node mm/slub.c:5413 [inline]
       __kmalloc_noprof+0xbc/0x720 mm/slub.c:5439
       _kmalloc_noprof include/linux/slab.h:995 [inline]
       _kzalloc_noprof include/linux/slab.h:1312 [inline]
       kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
       kobject_move+0x2fa/0x720 lib/kobject.c:556
       device_move+0xe0/0x720 drivers/base/core.c:4693
       hci_conn_del_sysfs+0xb8/0x1a0 net/bluetooth/hci_sysfs.c:75
       hci_conn_cleanup net/bluetooth/hci_conn.c:170 [inline]
       hci_conn_del+0xc3d/0x1200 net/bluetooth/hci_conn.c:1318
       hci_abort_conn_sync+0xdd0/0x1190 net/bluetooth/hci_sync.c:5994
       hci_cmd_sync_work+0x20b/0x3f0 net/bluetooth/hci_sync.c:332
       process_one_work kernel/workqueue.c:3396 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
       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 --> dpm_list_mtx

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(dpm_list_mtx);
                               lock(cpuhp_state-up);
                               lock(dpm_list_mtx);
  lock(fs_reclaim);

 *** DEADLOCK ***

locks held by kworker/u9:0/18686: 5, last CPU#0:
 #0: ffff88802515f940 ((wq_completion)hci4){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88802515f940 ((wq_completion)hci4){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88802515f940 ((wq_completion)hci4){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88802515f940 ((wq_completion)hci4){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc9000255fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc9000255fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc9000255fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc9000255fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff88803e494ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x1cb/0x3f0 net/bluetooth/hci_sync.c:331
 #3: ffff88803e4940b8 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0xa6f/0x1190 net/bluetooth/hci_sync.c:5975
 #4: ffffffff8f8120c0 (dpm_list_mtx){+.+.}-{4:4}, at: device_move+0x3c/0x720 drivers/base/core.c:4682

stack backtrace:
CPU: 0 UID: 0 PID: 18686 Comm: kworker/u9:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: hci4 hci_cmd_sync_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191
 check_prev_add kernel/locking/lockdep.c:3181 [inline]
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
 __fs_reclaim_acquire mm/page_alloc.c:4375 [inline]
 fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4389
 might_alloc include/linux/sched/mm.h:316 [inline]
 slab_pre_alloc_hook mm/slub.c:4636 [inline]
 slab_alloc_node mm/slub.c:4974 [inline]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_noprof+0xbc/0x720 mm/slub.c:5439
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
 kobject_move+0x2fa/0x720 lib/kobject.c:556
 device_move+0xe0/0x720 drivers/base/core.c:4693
 hci_conn_del_sysfs+0xb8/0x1a0 net/bluetooth/hci_sysfs.c:75
 hci_conn_cleanup net/bluetooth/hci_conn.c:170 [inline]
 hci_conn_del+0xc3d/0x1200 net/bluetooth/hci_conn.c:1318
 hci_abort_conn_sync+0xdd0/0x1190 net/bluetooth/hci_sync.c:5994
 hci_cmd_sync_work+0x20b/0x3f0 net/bluetooth/hci_sync.c:332
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 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
 </TASK>