INFO: rcu detected stall in br_ioctl_stub (2)

Status: upstream: reported on 2026/10/09 10:22
Reported-by: syzbot+a418cf57c129438be992@syzkaller.appspotmail.com
First crash: 4d06h, last: 4d06h
▶ ▼ Similar bugs (6)
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 363d 363d 0/3 auto-obsoleted due to no activity on 2026/01/22 19:15
linux-6.1 INFO: rcu detected stall in br_ioctl_stub (3) 1 1 76d 76d 0/3 upstream: reported on 2026/07/29 13:42
linux-6.1 INFO: rcu detected stall in br_ioctl_stub (2) 1 1 256d 256d 0/3 auto-obsoleted due to no activity on 2026/05/10 08:26
upstream INFO: rcu detected stall in br_ioctl_stub mm 1 1 455d 455d 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 2 184d 282d 0/3 auto-obsoleted due to no activity on 2026/07/21 15:41
android-5-15 BUG: soft lockup in br_ioctl_stub 1 4 830d 901d 0/2 auto-obsoleted due to no activity on 2024/10/02 18:03

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=589/1/0x4000000000000002 softirq=12177/12178 fqs=5245 
	(detected by 1, t=10502 jiffies, g=16145, q=1449)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5936 Comm: syz.7.334 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:__sanitizer_cov_trace_pc+0x58/0x60 kernel/kcov.c:215
Code: 10 16 00 00 83 fa 02 75 21 48 8b 91 18 16 00 00 48 8b 32 48 8d 7e 01 8b 89 14 16 00 00 48 39 cf 73 08 48 89 44 f2 08 48 89 3a <c3> 0f 1f 80 00 00 00 00 48 8b 04 24 65 48 8b 0d f4 4b 89 7e 65 8b
RSP: 0018:ffffc90000007638 EFLAGS: 00000046
RAX: ffffffff8198a5f3 RBX: ffff8880b8e35250 RCX: ffff888027490000
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc900000078c8 R08: ffffffff8e6b282f R09: 1ffffffff1cd6505
R10: dffffc0000000000 R11: fffffbfff1cd6506 R12: 1ffff110171c6a4a
R13: ffff88807a9b9dd8 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f5d6e4ef6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5ce0dd7a10 CR3: 0000000023f8c000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_tp_event+0x363/0xbe0 kernel/events/core.c:10055
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
 perf_trace_preemptirq_template+0x2aa/0x360 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+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
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 82 fc 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007b00 EFLAGS: 00000206
RAX: 5e33360a427f0e00 RBX: 1ffff92000000f64 RCX: 5e33360a427f0e00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4c00
RBP: ffffc90000007bd8 R08: ffffffff910150cf R09: 1ffffffff2202a19
R10: dffffc0000000000 R11: fffffbfff2202a1a R12: ffffffff8d123400
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+0x4ea/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 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:finish_lock_switch+0x12f/0x290 kernel/sched/core.c:4804
Code: 83 c7 18 be ff ff ff ff e8 be bc 6d 08 85 c0 74 46 4d 85 ff 75 62 0f 1f 44 00 00 48 89 df e8 58 2d 77 08 e8 a3 f2 2a 00 fb 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 2f 0e fe ff 43 80 3c 2c
RSP: 0018:ffffc900032ef4d8 EFLAGS: 00000286
RAX: 5e33360a427f0e00 RBX: ffff88802cbd0000 RCX: 5e33360a427f0e00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4c00
RBP: 1ffff110171c7613 R08: ffffffff910150cf R09: 1ffffffff2202a19
R10: dffffc0000000000 R11: fffffbfff2202a1a R12: 1ffff110171c75c1
R13: dffffc0000000000 R14: ffff8880b8e3ae08 R15: 0000000000000000
 finish_task_switch+0x12f/0x650 kernel/sched/core.c:4921
 context_switch kernel/sched/core.c:5052 [inline]
 __schedule+0x11cb/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:435
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:kasan_quarantine_put+0x84/0x210 mm/kasan/quarantine.c:234
Code: e8 31 df c0 ff 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 0f 85 83 00 00 00 41 f7 c7 00 02 00 00 74 01 fb 31 c0 <48> 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f c3 48 8d 80 40 62 03 00 45
RSP: 0018:ffffc900032ef8a0 EFLAGS: 00000206
RAX: 5e33360a427f0e01 RBX: ffff888024d30b40 RCX: 5e33360a427f0e00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4c00
RBP: ffffc900032ef930 R08: ffffffff910150cf R09: 1ffffffff2202a19
R10: dffffc0000000000 R11: fffffbfff2202a1a R12: ffff888017841500
R13: ffff888024d30b40 R14: 00000000000d2f20 R15: 0000000000000282
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 kobject_uevent_env+0x363/0x890 lib/kobject_uevent.c:640
 device_add+0xac2/0x1050 drivers/base/core.c:3393
 netdev_register_kobject+0x184/0x320 net/core/net-sysfs.c:2014
 register_netdevice+0x10e8/0x1720 net/core/dev.c:10423
 br_add_bridge+0x9f/0xe0 net/bridge/br_if.c:463
 br_ioctl_stub+0x4f5/0xbe0 net/bridge/br_ioctl.c:416
 br_ioctl_call net/socket.c:1122 [inline]
 sock_ioctl+0x453/0x700 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: 0033:0x7f5d702971d9
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:00007f5d6e4ef028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5d7051efa0 RCX: 00007f5d702971d9
RDX: 0000200000000080 RSI: 00000000000089a0 RDI: 000000000000000f
RBP: 00007f5d7032e888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5d7051f038 R14: 00007f5d7051efa0 R15: 00007ffd44fac578
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/09 10:22 linux-5.15.y a051a4bf909f b2734a59 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in br_ioctl_stub
* Struck through repros no longer work on HEAD.