[syzbot] [bluetooth?] WARNING in hci_conn_drop (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=13f0ebce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a834c6344141a58b
dashboard link: https://syzkaller.appspot.com/bug?extid=195b4c12c5b8c9a8eb8b
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+195b4c...@syzkaller.appspotmail.com

------------[ cut here ]------------
workqueue: cannot queue hci_conn_timeout on wq hci4
WARNING: kernel/workqueue.c:2298 at __queue_work+0xf6c/0x12f8 kernel/workqueue.c:2296, CPU#0: kworker/0:5/4769
Modules linked in:
CPU: 0 UID: 0 PID: 4769 Comm: kworker/0:5 Tainted: G L syzkaller #0 PREEMPT
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events l2cap_chan_timeout
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 : ffff800092887810
x29: ffff800092887850 x28: ffff700012510f78 x27: ffff0000d64aba88
x26: ffff0000d629f800 x25: 0000000000000008 x24: ffff0000d629f9c0
x23: dfff800000000000 x22: ffff0000de09572c x21: 0000000004208060
x20: ffff800089f06000 x19: ffff0000c5968a58 x18: 1fffe00035c20e20
x17: ffff8000888db000 x16: ffff80008898cfc0 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000ff0100 x9 : 2aca8fde2d60a500
x8 : 2aca8fde2d60a500 x7 : ffff8000804886d0 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000000 x3 : ffff8000802f13b0
x2 : 0000000100000000 x1 : ffff0000de095700 x0 : 0000000000000000
Call trace:
__queue_work+0xf6c/0x12f8 kernel/workqueue.c:2296 (P)
__queue_delayed_work+0xf4/0x2b4 kernel/workqueue.c:2548
queue_delayed_work_on+0xcc/0x140 kernel/workqueue.c:2600
queue_delayed_work include/linux/workqueue.h:711 [inline]
hci_conn_drop+0x174/0x29c include/net/bluetooth/hci_core.h:1712
l2cap_chan_del+0x220/0x48c net/bluetooth/l2cap_core.c:672
l2cap_chan_close+0x3e4/0x5ac net/bluetooth/l2cap_core.c:-1
l2cap_chan_timeout+0x120/0x29c net/bluetooth/l2cap_core.c:431
process_one_work+0x78c/0x173c kernel/workqueue.c:3302
process_scheduled_works+0xdc/0x13c kernel/workqueue.c:3385
worker_thread+0x770/0xbd0 kernel/workqueue.c:3466
kthread+0x2f0/0x3c0 kernel/kthread.c:436
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842
irq event stamp: 81246
hardirqs last enabled at (81245): [<ffff800080351f60>] __cancel_work+0xf4/0x1a4 kernel/workqueue.c:4454
hardirqs last disabled at (81246): [<ffff80008034e144>] queue_delayed_work_on+0x54/0x140 kernel/workqueue.c:2596
softirqs last enabled at (81238): [<ffff800084aa1108>] spin_unlock_bh include/linux/spinlock.h:396 [inline]
softirqs last enabled at (81238): [<ffff800084aa1108>] release_sock+0x150/0x228 net/core/sock.c:3825
softirqs last disabled at (81234): [<ffff800084aa0fec>] spin_lock_bh include/linux/spinlock.h:348 [inline]
softirqs last disabled at (81234): [<ffff800084aa0fec>] release_sock+0x34/0x228 net/core/sock.c:3812
---[ end trace 0000000000000000 ]---


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