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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 68efe5a6c16a Linux 5.15.197
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=135c0074580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7e6ed99963d6ee1d
dashboard link: https://syzkaller.appspot.com/bug?extid=2c418506f23547356f3b
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/998e4247f9d0/disk-68efe5a6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ef4066c91ec/vmlinux-68efe5a6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/922e7b640c48/bzImage-68efe5a6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2c4185...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 GPs behind) idle=745/1/0x4000000000000002 softirq=19839/19841 fqs=2095
(detected by 1, t=10505 jiffies, g=27381, q=314)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8371 Comm: syz.5.971 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:192 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4711 [inline]
RIP: 0010:__lock_acquire+0x8e7/0x7c60 kernel/locking/lockdep.c:4962
Code: c0 48 69 69 8d 48 c1 e8 03 48 89 84 24 b0 00 00 00 4d 89 e7 48 83 fb 31 0f 83 52 01 00 00 4c 89 f8 48 c1 e8 03 42 0f b6 04 00 <84> c0 0f 85 5c 01 00 00 41 8b 04 24 41 89 c6 41 81 e6 ff 1f 00 00
RSP: 0018:ffffc90000006f40 EFLAGS: 00000806
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ffaa0c0
RBP: ffffc90000007190 R08: dffffc0000000000 R09: fffffbfff1ff5419
R10: fffffbfff1ff5419 R11: 1ffffffff1ff5418 R12: ffff888024a80b88
R13: 0000000000000002 R14: ffffffff8f932ff8 R15: ffff888024a80b88
FS: 00007f371beeb6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c31a420 CR3: 00000000199ee000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
__task_pid_nr_ns+0x21/0x420 kernel/pid.c:497
perf_event_pid_type kernel/events/core.c:1446 [inline]
perf_event_tid kernel/events/core.c:1460 [inline]
__perf_event_header__init_id+0x20b/0x500 kernel/events/core.c:7106
perf_prepare_sample+0x158/0x1cb0 kernel/events/core.c:7624
__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_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 ed 11 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:ffffc90000007ae0 EFLAGS: 00000206
RAX: fc5f3e13f2256400 RBX: 1ffff92000000f60 RCX: fc5f3e13f2256400
RDX: dffffc0000000000 RSI: ffffffff8a0b1be0 RDI: ffffffff8a59e800
RBP: ffffc90000007bb8 R08: dffffc0000000000 R09: fffffbfff1ff541a
R10: fffffbfff1ff541a R11: 1ffffffff1ff5419 R12: ffffffff8c120c00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:772 [inline]
ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x53d/0xc40 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
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:__dev_alloc_name+0x467/0x7d0 net/core/dev.c:1148
Code: 10 48 8b 1c 24 0f 84 df 02 00 00 4c 89 74 24 30 48 89 44 24 08 4c 8d 70 d0 4c 89 f0 48 c1 e8 03 48 89 44 24 38 42 80 3c 28 00 <74> 08 4c 89 f7 e8 ff 24 eb f9 4d 8b 2e 49 83 c5 10 4c 89 e8 48 c1
RSP: 0018:ffffc9000332fa00 EFLAGS: 00000246
RAX: 1ffff1100f041802 RBX: ffff88807820c040 RCX: 0000000000080000
RDX: ffffc9001441d000 RSI: 0000000000019e84 RDI: 0000000000019e85
RBP: ffffc9000332fad8 R08: ffff888024a80000 R09: 0000000000000004
R10: 0000000000000008 R11: 0000000000000002 R12: ffffc9000332fc00
R13: dffffc0000000000 R14: ffff88807820c010 R15: 1ffff92000665f48
dev_prep_valid_name+0x1cc/0x330 net/core/dev.c:1194
dev_get_valid_name net/core/dev.c:1245 [inline]
register_netdevice+0x494/0x16b0 net/core/dev.c:10316
br_add_bridge+0x9f/0xe0 net/bridge/br_if.c:460
br_ioctl_stub+0x351/0x8e0 net/bridge/br_ioctl.c:-1
br_ioctl_call net/socket.c:1124 [inline]
sock_ioctl+0x2f1/0x6e0 net/socket.c:1221
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f371dc84749
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:00007f371beeb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f371dedafa0 RCX: 00007f371dc84749
RDX: 00002000000000c0 RSI: 00000000000089a0 RDI: 0000000000000006
RBP: 00007f371dd08f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f371dedb038 R14: 00007f371dedafa0 R15: 00007fffdda43c18
</TASK>


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