INFO: task syz.0.17:5040 blocked for more than 143 seconds.
      Not tainted 5.15.186-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:25864 pid: 5040 ppid:  4792 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x97/0x280 kernel/time/timer.c:1890
 do_wait_for_common+0x29a/0x440 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 kthread_stop+0x16e/0x540 kernel/kthread.c:666
 ext4_stop_mmpd+0x43/0xb0 fs/ext4/mmp.c:263
 ext4_fill_super+0x6608/0x9a00 fs/ext4/super.c:5086
 mount_bdev+0x287/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3014
 do_mount fs/namespace.c:3357 [inline]
 __do_sys_mount fs/namespace.c:3565 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0a2aefe90a
RSP: 002b:00007f0a2a16de68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f0a2a16def0 RCX: 00007f0a2aefe90a
RDX: 0000400000000040 RSI: 0000400000000000 RDI: 00007f0a2a16deb0
RBP: 0000400000000040 R08: 00007f0a2a16def0 R09: 0000000003010008
R10: 0000000003010008 R11: 0000000000000246 R12: 0000400000000000
R13: 00007f0a2a16deb0 R14: 0000000000000538 R15: 0000400000000340
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u4:0/9:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3940:
 #0: ffff88802b651098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002ce62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz.0.17/5040:
 #0: ffff8880693140e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.1.19/5066:
 #0: ffff88802609c0e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.2.20/5090:
 #0: ffff888022a360e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.3.23/5120:
 #0: ffff8880683740e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.4.29/5167:
 #0: ffff88801e5bc0e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.5.30/5195:
 #0: ffff8880571680e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.6.32/5227:
 #0: ffff888023cf80e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.7.36/5270:
 #0: ffff8880747d80e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.8.37/5299:
 #0: ffff8880210240e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4268 Comm: kworker/u5:2 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci9 hci_cmd_work
RIP: 0010:_find_first_zero_bit+0xb5/0xf0 lib/find_bit.c:101
Code: df 73 31 4c 89 e0 48 c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 4d ac e2 fd 4d 8b 2e 49 83 fd ff 75 1d e8 3f 33 9d fd 49 83 c4 08 <49> 83 c6 08 49 83 c7 40 eb bf e8 2c 33 9d fd 48 89 d8 eb 17 e8 22
RSP: 0018:ffffc9000303f4e8 EFLAGS: 00000096
RAX: ffffffff83da8fd1 RBX: 0000000000100000 RCX: ffff888029928000
RDX: 0000000000000000 RSI: 0000000000100000 RDI: 0000000000005340
RBP: dffffc0000000000 R08: 0000000000000004 R09: 0000000000000003
R10: fffff52000607e94 R11: 1ffff92000607e94 R12: ffffffff8fae39f0
R13: ffffffffffffffff R14: ffffffff8fae39e8 R15: 0000000000005340
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556dda113048 CR3: 00000000219b3000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 find_first_zero_bit include/asm-generic/bitops/find.h:140 [inline]
 alloc_lock_chain kernel/locking/lockdep.c:3598 [inline]
 add_chain_cache kernel/locking/lockdep.c:3630 [inline]
 lookup_chain_cache_add kernel/locking/lockdep.c:3735 [inline]
 validate_chain kernel/locking/lockdep.c:3756 [inline]
 __lock_acquire+0x14f3/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 try_to_wake_up+0x5c/0x1050 kernel/sched/core.c:4030
 autoremove_wake_function+0x13/0xf0 kernel/sched/wait.c:416
 __wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:108
 __wake_up_common_lock kernel/sched/wait.c:138 [inline]
 __wake_up+0x108/0x180 kernel/sched/wait.c:157
 vhci_send_frame+0xb4/0x100 drivers/bluetooth/hci_vhci.c:75
 hci_send_frame+0x1a9/0x2e0 net/bluetooth/hci_core.c:4256
 hci_cmd_work+0x1b7/0x360 net/bluetooth/hci_core.c:5201
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>