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INFO: rcu detected stall in br_ioctl_stub (2)

Status: upstream: reported on 2026/01/30 08:26
Reported-by: syzbot+126d2d2d2adf5ed776e9@syzkaller.appspotmail.com
First crash: 1d21h, last: 1d21h
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in br_ioctl_stub 1 1 109d 109d 0/3 auto-obsoleted due to no activity on 2026/01/22 19:15
upstream INFO: rcu detected stall in br_ioctl_stub mm 1 1 200d 200d 0/29 auto-obsoleted due to no activity on 2025/10/13 06:56
linux-5.15 INFO: rcu detected stall in br_ioctl_stub 1 1 28d 28d 0/3 upstream: reported on 2026/01/03 21:20
android-5-15 BUG: soft lockup in br_ioctl_stub 1 4 576d 647d 0/2 auto-obsoleted due to no activity on 2024/10/02 18:03

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2679 jiffies s: 119629 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: 25568 Comm: syz.2.6874 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 ef 2f 01 03 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900001e04c8 EFLAGS: 00000046
RAX: 00000000000000f6 RBX: ffffffff8c64fb88 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000001 R08: ffffc900001e0447 R09: 1ffff9200003c088
R10: dffffc0000000000 R11: fffff5200003c089 R12: 0000000000000000
R13: dffffc0000000001 R14: dffffc0000000000 R15: 0000000000000001
FS:  00007f8625dde6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2ad7e2 CR3: 0000000062358000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000200000000380 DR2: 0000000000000000
DR3: 0000000000008d24 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 arch_irq_work_raise+0x82/0xd0 arch/x86/kernel/irq_work.c:31
 irq_work_queue_on+0x13c/0x260 kernel/irq_work.c:165
 rcu_read_unlock_special+0x3c9/0x510 kernel/rcu/tree_plugin.h:678
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 trace_call_bpf+0x5bb/0x6b0 kernel/trace/bpf_trace.c:137
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:9997
 perf_trace_preemptirq_template+0x268/0x320 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+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 92 30 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900001e0980 EFLAGS: 00000206
RAX: 5a6c814c2f115700 RBX: 1ffff9200003c138 RCX: 5a6c814c2f115700
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0c20
RBP: ffffc900001e0a80 R08: ffffffff90af332f R09: 1ffffffff215e665
R10: dffffc0000000000 R11: fffffbfff215e666 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]
 hsr_announce+0x2ca/0x340 net/hsr/hsr_device.c:407
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 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:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:preempt_latency_stop kernel/sched/core.c:5728 [inline]
RIP: 0010:preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6732
Code: 49 81 c6 d8 14 00 00 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 1b 6b 9e f7 49 89 1e bf 01 00 00 00 e8 9e bb ff ff <65> 8b 05 6f 7c cd 75 65 ff 0d 68 7c cd 75 65 48 8b 1d 58 7c cd 75
RSP: 0018:ffffc9000497f420 EFLAGS: 00000246
RAX: 5a6c814c2f115700 RBX: ffffffff8a34f23c RCX: 5a6c814c2f115700
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffff88801eaed178
RBP: ffffc9000497f4b8 R08: ffffffff90af324f R09: 1ffffffff215e649
R10: dffffc0000000000 R11: fffffbfff215e64a R12: ffff8880b8f3a040
R13: 0000000000045e21 R14: ffff88801eaed058 R15: dffffc0000000000
 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6755
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 idr_preload_end include/linux/idr.h:174 [inline]
 __kernfs_new_node+0x625/0x810 fs/kernfs/dir.c:626
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:690
 __kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:1068
 sysfs_add_file_mode_ns+0x234/0x2f0 fs/sysfs/file.c:294
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x493/0xcf0 fs/sysfs/group.c:148
 internal_create_groups fs/sysfs/group.c:188 [inline]
 sysfs_create_groups+0x55/0x120 fs/sysfs/group.c:214
 device_add_groups drivers/base/core.c:2752 [inline]
 device_add_attrs+0xdb/0x830 drivers/base/core.c:2900
 device_add+0x64b/0xfb0 drivers/base/core.c:3648
 netdev_register_kobject+0x184/0x320 net/core/net-sysfs.c:2013
 register_netdevice+0x12dd/0x1ae0 net/core/dev.c:10204
 br_add_bridge+0x9f/0xe0 net/bridge/br_if.c:470
 br_ioctl_stub+0x5e2/0xcf0 net/bridge/br_ioctl.c:442
 br_ioctl_call net/socket.c:1175 [inline]
 sock_ioctl+0x494/0x710 net/socket.c:1274
 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:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8624f9aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8625dde028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8625215fa0 RCX: 00007f8624f9aeb9
RDX: 0000200000000080 RSI: 00000000000089a0 RDI: 000000000000000c
RBP: 00007f8625008c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8625216038 R14: 00007f8625215fa0 R15: 00007fffdae430a8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/30 08:25 linux-6.1.y cd9b81672742 bfa73b7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in br_ioctl_stub
* Struck through repros no longer work on HEAD.