[syzbot] [bluetooth?] WARNING in hci_send_acl (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5cbb61bf4168 arm64/fpsimd: ptrace: zero target's fpsimd_st..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=138bd02e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a834c6344141a58b
dashboard link: https://syzkaller.appspot.com/bug?extid=0e3882021d9c3ae26430
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/04156ec16593/disk-5cbb61bf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6bfa041e2c79/vmlinux-5cbb61bf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a92d82d8a79e/Image-5cbb61bf.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0e3882...@syzkaller.appspotmail.com

------------[ cut here ]------------
workqueue: cannot queue hci_tx_work on wq hci2
WARNING: kernel/workqueue.c:2298 at __queue_work+0xf6c/0x12f8 kernel/workqueue.c:2296, CPU#0: kbnepd /10362
Modules linked in:
CPU: 0 UID: 0 PID: 10362 Comm: kbnepd Tainted: G L syzkaller #0 PREEMPT
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 634000c5 (nZCv daIF +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __queue_work+0xf6c/0x12f8 kernel/workqueue.c:2296
lr : __queue_work+0xf6c/0x12f8 kernel/workqueue.c:2296
sp : ffff8000971a7560
x29: ffff8000971a75a0 x28: ffff0000ed3e98c0 x27: ffff0000ed3e9990
x26: ffff0000ca68f800 x25: 0000000000000008 x24: ffff0000ca68f9c0
x23: dfff800000000000 x22: ffff0000d8bb002c x21: 0000000000208040
x20: ffff800089f06000 x19: ffff0000ce2d0c50 x18: 1fffe00035c20e20
x17: ffff8000888db000 x16: ffff80008898cfc0 x15: ffff0001ae10710c
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000001c1f x10: 0000000000ff0100 x9 : 2106f328601d6d00
x8 : 2106f328601d6d00 x7 : ffff8000804886d0 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000000 x3 : ffff8000802f13b0
x2 : 0000000100000000 x1 : ffff0000d8bb0000 x0 : 0000000000000000
Call trace:
__queue_work+0xf6c/0x12f8 kernel/workqueue.c:2296 (P)
queue_work_on+0xc0/0x130 kernel/workqueue.c:2432
queue_work include/linux/workqueue.h:696 [inline]
hci_send_acl+0x4a4/0x7c4 net/bluetooth/hci_core.c:3283
l2cap_do_send+0x18c/0x2b4 net/bluetooth/l2cap_core.c:1019
l2cap_chan_send+0x108c/0x1dc4 net/bluetooth/l2cap_core.c:-1
l2cap_sock_sendmsg+0x284/0x428 net/bluetooth/l2cap_sock.c:1164
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg+0xc8/0x138 net/socket.c:802
sock_sendmsg+0x154/0x228 net/socket.c:825
kernel_sendmsg+0x54/0x6c net/socket.c:849
bnep_tx_frame net/bluetooth/bnep/core.c:466 [inline]
bnep_session+0x1ce0/0x2298 net/bluetooth/bnep/core.c:509
kthread+0x2f0/0x3c0 kernel/kthread.c:436
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842
irq event stamp: 284
hardirqs last enabled at (283): [<ffff8000803bd554>] raw_spin_rq_unlock_irq kernel/sched/sched.h:1644 [inline]
hardirqs last enabled at (283): [<ffff8000803bd554>] finish_lock_switch+0x160/0x204 kernel/sched/core.c:5124
hardirqs last disabled at (284): [<ffff80008034c854>] queue_work_on+0x4c/0x130 kernel/workqueue.c:2428
softirqs last enabled at (236): [<ffff800084ab928c>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (232): [<ffff800084ab9258>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---


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