[v5.15] INFO: rcu detected stall in hci_cmd_work

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 29e53a5b1c4f Linux 5.15.194
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=125a5b34580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=ad1ac907adb506cbe3cf
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6cf4d5e6e441/disk-29e53a5b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b332ae2ff099/vmlinux-29e53a5b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f344d06d6b9/bzImage-29e53a5b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ad1ac9...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 GPs behind) idle=daf/1/0x4000000000000002 softirq=18664/18666 fqs=5247
(detected by 1, t=10502 jiffies, g=24477, q=2039)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4183 Comm: kworker/u5:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: hci2 hci_cmd_work
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:-1 [inline]
RIP: 0010:rcu_is_watching+0x40/0xa0 kernel/rcu/tree.c:1123
Code: 73 5c 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd 20 28 bc 8b 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 b0 82 58 00 <48> c7 c3 08 b3 03 00 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38
RSP: 0018:ffffc90000007208 EFLAGS: 00000046
RAX: 1ffffffff1778504 RBX: 0000000000000000 RCX: 68124d71f4c43c00
RDX: 0000000000000100 RSI: ffffffff8a59a4a0 RDI: ffffffff8a59a460
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffc900000073a0
R10: fffff52000000e7b R11: 1ffff92000000e74 R12: dffffc0000000000
R13: ffffc90000007406 R14: ffffffff8bbc2820 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f672a40cf98 CR3: 000000000be8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
rcu_read_lock_held_common kernel/rcu/update.c:108 [inline]
rcu_read_lock_held+0x11/0x40 kernel/rcu/update.c:309
perf_get_guest_cbs include/linux/perf_event.h:1274 [inline]
perf_misc_flags+0x56/0x1b0 arch/x86/events/core.c:2961
perf_prepare_sample+0x132/0x1cb0 kernel/events/core.c:7622
__perf_event_output kernel/events/core.c:7802 [inline]
perf_event_output_forward+0x146/0x280 kernel/events/core.c:7822
__perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
perf_swevent_overflow kernel/events/core.c:9591 [inline]
perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9629
perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
perf_trace_preemptirq_template+0x2be/0x380 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 ad 13 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007a00 EFLAGS: 00000206
RAX: 68124d71f4c43c00 RBX: 1ffff92000000f44 RCX: 68124d71f4c43c00
RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: ffffffff8a59a4c0
RBP: ffffc90000007ae0 R08: dffffc0000000000 R09: fffffbfff1ff7a36
R10: fffffbfff1ff7a36 R11: 1ffffffff1ff7a35 R12: ffffffff8c120b00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:771 [inline]
process_backlog+0x3e3/0x780 net/core/dev.c:6517
__napi_poll+0xc0/0x430 net/core/dev.c:7075
napi_poll net/core/dev.c:7142 [inline]
net_rx_action+0x4a8/0x9c0 net/core/dev.c:7232
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 ae 4b cb f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 36 d5 9e f7 65 8b 05 17 d3 4f 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90002effa20 EFLAGS: 00000206
RAX: 68124d71f4c43c00 RBX: 0000000000000a06 RCX: 68124d71f4c43c00
RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: 0000000000000001
RBP: ffffc90002effaa8 R08: dffffc0000000000 R09: fffffbfff1ff7a36
R10: fffffbfff1ff7a36 R11: 1ffffffff1ff7a35 R12: dffffc0000000000
R13: ffff888022571500 R14: ffffffff963682a0 R15: 1ffff920005dff44
__debug_check_no_obj_freed lib/debugobjects.c:982 [inline]
debug_check_no_obj_freed+0x515/0x530 lib/debugobjects.c:1003
slab_free_hook mm/slub.c:1685 [inline]
slab_free_freelist_hook+0x8b/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kmem_cache_free+0x8f/0x210 mm/slub.c:3520
kfree_skb include/linux/skbuff.h:1118 [inline]
hci_cmd_work+0xb4/0x360 net/bluetooth/hci_core.c:5194
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>


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