syzbot

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workqueue: cannot queue hci_conn_timeout on wq hci4
WARNING: kernel/workqueue.c:2252 at __queue_work+0xd5d/0xff0 kernel/workqueue.c:2250, CPU#0: kworker/0:10/6240
Modules linked in:
CPU: 0 UID: 0 PID: 6240 Comm: kworker/0:10 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events l2cap_chan_timeout
RIP: 0010:__queue_work+0xd88/0xff0 kernel/workqueue.c:2250
Code: 83 c5 18 4c 89 e8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ef e8 79 ac 97 00 49 8b 75 00 49 81 c7 68 01 00 00 4c 89 f7 4c 89 fa <67> 48 0f b9 3a 48 83 c4 58 5b 41 5c 41 5d 41 5e 41 5f 5d e9 80 18
RSP: 0018:ffffc90005d9f848 EFLAGS: 00010082
RAX: 1ffff11006a0015b RBX: 0000000000000008 RCX: ffff888023c09e40
RDX: ffff88803f866168 RSI: ffffffff89cd7580 RDI: ffffffff8eddefc0
RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1006a00159 R12: dffffc0000000000
R13: ffff888035000ad8 R14: ffffffff8eddefc0 R15: ffff88803f866168
FS:  0000000000000000(0000) GS:ffff888126cef000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f25a01d58 CR3: 000000002c666000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 queue_delayed_work_on+0x11a/0x1d0 kernel/workqueue.c:2555
 l2cap_chan_del+0x285/0x620 net/bluetooth/l2cap_core.c:672
 l2cap_chan_close+0x4c2/0x760 net/bluetooth/l2cap_core.c:-1
 l2cap_chan_timeout+0x158/0x3b0 net/bluetooth/l2cap_core.c:431
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess):
   0:	83 c5 18             	add    $0x18,%ebp
   3:	4c 89 e8             	mov    %r13,%rax
   6:	48 c1 e8 03          	shr    $0x3,%rax
   a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
   f:	74 08                	je     0x19
  11:	4c 89 ef             	mov    %r13,%rdi
  14:	e8 79 ac 97 00       	call   0x97ac92
  19:	49 8b 75 00          	mov    0x0(%r13),%rsi
  1d:	49 81 c7 68 01 00 00 	add    $0x168,%r15
  24:	4c 89 f7             	mov    %r14,%rdi
  27:	4c 89 fa             	mov    %r15,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	48 83 c4 58          	add    $0x58,%rsp
  33:	5b                   	pop    %rbx
  34:	41 5c                	pop    %r12
  36:	41 5d                	pop    %r13
  38:	41 5e                	pop    %r14
  3a:	41 5f                	pop    %r15
  3c:	5d                   	pop    %rbp
  3d:	e9                   	.byte 0xe9
  3e:	80                   	.byte 0x80
  3f:	18                   	.byte 0x18