EXT4-fs warning (device loop9): ext4_begin_enable_verity:135: inode #18: comm syz.9.8796: verity is only allowed on extent-based files
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.9.8796/25729 is trying to acquire lock:
ffff88810f09c0b8 (&hdev->lock){+.+.}-{4:4}, at: l2cap_chan_connect+0x9c/0x1110

but task is already holding lock:
ffffffff903fbea0 (rfcomm_mutex){+.+.}-{4:4}, at: rfcomm_dlc_open+0x9c/0x1080

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (rfcomm_mutex){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1550
       rfcomm_security_cfm+0x90/0x820
       hci_auth_complete_evt+0x39f/0xc80
       hci_event_packet+0x6cd/0xf10
       hci_rx_work+0x3ee/0x1020
       process_scheduled_works+0xc3d/0x1630
       worker_thread+0xa47/0xfb0
       kthread+0x38b/0x480
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #1 (hci_cb_list_lock){+.+.}-{4:4}:
       __mutex_lock+0x19d/0x1550
       hci_remote_features_evt+0x53d/0x950
       hci_event_packet+0x6cd/0xf10
       hci_rx_work+0x3ee/0x1020
       process_scheduled_works+0xc3d/0x1630
       worker_thread+0xa47/0xfb0
       kthread+0x38b/0x480
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #0 (&hdev->lock){+.+.}-{4:4}:
       __lock_acquire+0x15ff/0x2e50
       lock_acquire+0x115/0x350
       __mutex_lock+0x19d/0x1550
       l2cap_chan_connect+0x9c/0x1110
       l2cap_sock_connect+0x5e4/0x7e0
       kernel_connect+0x141/0x1c0
       rfcomm_dlc_open+0x644/0x1080
       rfcomm_sock_connect+0x2ed/0x650
       __sys_connect+0x316/0x450
       __x64_sys_connect+0x7a/0x90
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &hdev->lock --> hci_cb_list_lock --> rfcomm_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(rfcomm_mutex);
                               lock(hci_cb_list_lock);
                               lock(rfcomm_mutex);
  lock(&hdev->lock);

 *** DEADLOCK ***

locks held by syz.9.8796/25729: 1, last CPU#0:
 #0: ffffffff903fbea0 (rfcomm_mutex){+.+.}-{4:4}, at: rfcomm_dlc_open+0x9c/0x1080

stack backtrace:
CPU: 0 UID: 0 PID: 25729 Comm: syz.9.8796 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_circular_bug+0x2e2/0x300
 check_noncircular+0x12f/0x150
 __lock_acquire+0x15ff/0x2e50
 lock_acquire+0x115/0x350
 __mutex_lock+0x19d/0x1550
 l2cap_chan_connect+0x9c/0x1110
 l2cap_sock_connect+0x5e4/0x7e0
 kernel_connect+0x141/0x1c0
 rfcomm_dlc_open+0x644/0x1080
 rfcomm_sock_connect+0x2ed/0x650
 __sys_connect+0x316/0x450
 __x64_sys_connect+0x7a/0x90
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fce3fb9e159
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:00007fce40a31028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fce3fe25fa0 RCX: 00007fce3fb9e159
RDX: 000000000000000a RSI: 0000200000000080 RDI: 0000000000000007
RBP: 00007fce3fc35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fce3fe26038 R14: 00007fce3fe25fa0 R15: 00007ffe679778a8
 </TASK>
