[v6.1] INFO: rcu detected stall in br_ioctl_stub

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 882efbdd9d34 Linux 6.1.155
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1637f304580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=15b9d8a5d8986f2bbf4b
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/9e95032679d0/disk-882efbdd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a435805a627b/vmlinux-882efbdd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d15d65ba922d/bzImage-882efbdd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+15b9d8...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2637 jiffies s: 46105 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8713 Comm: syz.6.1095 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:perf_output_begin_forward+0x703/0xa80 kernel/events/ring_buffer.c:272
Code: 48 89 df e8 5f 19 2a 00 4c 89 33 48 83 7c 24 60 00 0f 85 e4 01 00 00 e8 ab eb d9 ff 31 db 48 c7 84 24 80 00 00 00 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900001e0340 EFLAGS: 00000046
RAX: f0772926ff2c2600 RBX: 00000000ffffffe4 RCX: f0772926ff2c2600
RDX: 0000000000000004 RSI: ffffffff8a8c1680 RDI: ffffffff8adefd20
RBP: ffffc900001e0470 R08: dffffc0000000000 R09: fffffbfff1c3ecb6
R10: fffffbfff1c3ecb6 R11: 1ffffffff1c3ecb5 R12: 1ffff9200003c078
R13: 0000000000000028 R14: ffffc900001e04c0 R15: dffffc0000000000
FS: 00007fd3dd9d56c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c288580 CR3: 000000005d25c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
__perf_event_output kernel/events/core.c:7732 [inline]
perf_event_output_forward+0x179/0x2a0 kernel/events/core.c:7750
__perf_event_overflow+0x448/0x610 kernel/events/core.c:9496
perf_tp_event+0x335/0xb60 kernel/events/core.c:10029
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10002
perf_trace_preemptirq_template+0x287/0x330 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x84/0x500 kernel/rcu/tree_plugin.h:685
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 2d 97 96 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc900001e0aa0 EFLAGS: 00000206
RAX: f0772926ff2c2600 RBX: 1ffff9200003c15c RCX: f0772926ff2c2600
RDX: dffffc0000000000 RSI: ffffffff8a8c0500 RDI: ffffffff8adefd20
RBP: ffffc900001e0b90 R08: dffffc0000000000 R09: fffffbfff215c44a
R10: fffffbfff215c44a R11: 1ffffffff215c449 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
ieee80211_iterate_active_interfaces_atomic+0x156/0x170 net/mac80211/util.c:826
mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2147
__run_hrtimer kernel/time/hrtimer.c:1747 [inline]
__hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1811
hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1828
handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 8e 80 65 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> 96 0b 36 f7 65 8b 05 97 c4 e0 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900039c7620 EFLAGS: 00000206
RAX: f0772926ff2c2600 RBX: 0000000000000a02 RCX: f0772926ff2c2600
RDX: dffffc0000000000 RSI: ffffffff8a8c0500 RDI: 0000000000000001
RBP: ffffc900039c76b8 R08: dffffc0000000000 R09: fffffbfff215c44a
R10: fffffbfff215c44a R11: 1ffffffff215c449 R12: dffffc0000000000
R13: ffff88805307d000 R14: ffffffff96eacbb8 R15: 1ffff92000738ec4
debug_timer_init kernel/time/timer.c:777 [inline]
debug_init kernel/time/timer.c:825 [inline]
init_timer_key+0x3e/0x320 kernel/time/timer.c:869
br_multicast_ctx_init+0x30f/0x4e0 net/bridge/br_multicast.c:3944
__vlan_add+0x4ca/0x26e0 net/bridge/br_vlan.c:328
br_vlan_add+0x449/0x920 net/bridge/br_vlan.c:803
br_vlan_bridge_event+0xf8/0x770 net/bridge/br_vlan.c:1741
br_device_event+0x154/0x880 net/bridge/br.c:40
notifier_call_chain kernel/notifier.c:87 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
call_netdevice_notifiers_extack net/core/dev.c:2039 [inline]
call_netdevice_notifiers net/core/dev.c:2053 [inline]
register_netdevice+0x1600/0x1aa0 net/core/dev.c:10237
br_add_bridge+0x9f/0xe0 net/bridge/br_if.c:469
br_ioctl_stub+0x456/0x9e0 net/bridge/br_ioctl.c:-1
br_ioctl_call net/socket.c:1178 [inline]
sock_ioctl+0x2f1/0x6e0 net/socket.c:1275
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd3df78eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd3dd9d5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd3df9e6090 RCX: 00007fd3df78eec9
RDX: 0000200000000080 RSI: 00000000000089a0 RDI: 0000000000000010
RBP: 00007fd3df811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd3df9e6128 R14: 00007fd3df9e6090 R15: 00007ffc0e649cd8
</TASK>


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