syzbot
INFO: rcu detected stall in br_handle_frame
Status:
upstream: reported on 2025/11/21 04:49
Reported-by: syzbot+a0b26fcabafa4609b88c@syzkaller.appspotmail.com
First crash: 287d, last: 20d
Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P10523/1:b..l
rcu: (detected by 1, t=10503 jiffies, g=34441, q=113 ncpus=2)
task:syz.1.1725 state:R running task stack:25832 pid:10523 ppid:5774 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__local_bh_enable_ip+0x14b/0x1c0 kernel/softirq.c:413
spin_unlock_bh include/linux/spinlock.h:396 [inline]
nl80211_netlink_notify+0x6fa/0x840 net/wireless/nl80211.c:20043
notifier_call_chain+0x18f/0x380 kernel/notifier.c:93
blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:388
netlink_release+0x1233/0x1a70 net/netlink/af_netlink.c:767
__sock_release net/socket.c:659 [inline]
sock_close+0xa7/0x210 net/socket.c:1421
__fput+0x221/0x940 fs/file_table.c:418
task_work_run+0x1d4/0x260 kernel/task_work.c:245
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x986/0x2530 kernel/exit.c:890
do_group_exit+0x22d/0x2f0 kernel/exit.c:1032
get_signal+0x12a6/0x1390 kernel/signal.c:2911
arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8b6b19e0d9
RSP: 002b:00007f8b6c07b028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000009 RBX: 00007f8b6b425fa0 RCX: 00007f8b6b19e0d9
RDX: 0000100000000000 RSI: 0000000000000000 RDI: 0000200000000180
RBP: 00007f8b6b235024 R08: 0000000000000002 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8b6b426038 R14: 00007f8b6b425fa0 R15: 00007ffd83a8b628
</TASK>
rcu: rcu_preempt kthread starved for 8807 jiffies! g34441 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:26504 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10540 Comm: syz.2.1730 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:deref_stack_reg+0x1b3/0x230 arch/x86/kernel/unwind_orc.c:406
Code: c1 4c 39 e0 0f 96 c0 84 c1 74 43 e8 67 a0 4b 00 49 bf 00 00 00 00 00 fc ff df 48 89 ef e8 b5 07 00 00 49 89 c6 48 8b 5c 24 10 <48> 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 07 24 a4 00
RSP: 0018:ffffc90000006ac0 EFLAGS: 00000006
RAX: ffffc90019847ee8 RBX: ffffc90000006c80 RCX: ffff88802bdfbc00
RDX: 0000000000010100 RSI: 0000000000000001 RDI: ffffc90019847d70
RBP: ffffc90019847d70 R08: ffff88802bdfbc00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000010100 R12: ffffc90019848000
R13: 1ffff92000000d8a R14: ffffc90019847ee8 R15: dffffc0000000000
FS: 00007f87bdbf66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e2e7000 CR3: 000000007ad41000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
unwind_next_frame+0x1781/0x2990 arch/x86/kernel/unwind_orc.c:648
perf_callchain_kernel+0x42e/0x690 arch/x86/events/core.c:2780
get_perf_callchain+0x231/0x510 kernel/events/callchain.c:204
perf_callchain kernel/events/core.c:7734 [inline]
perf_sample_save_callchain include/linux/perf_event.h:1232 [inline]
perf_prepare_sample+0x3c7/0x1db0 kernel/events/core.c:7778
__perf_event_output kernel/events/core.c:7966 [inline]
perf_event_output_forward+0x187/0x3e0 kernel/events/core.c:7987
__perf_event_overflow+0x461/0x660 kernel/events/core.c:9712
perf_event_overflow kernel/events/core.c:9733 [inline]
perf_swevent_hrtimer+0x437/0x610 kernel/events/core.c:11222
__run_hrtimer kernel/time/hrtimer.c:1754 [inline]
__hrtimer_run_queues+0x4e8/0xc10 kernel/time/hrtimer.c:1818
hrtimer_interrupt+0x39d/0x980 kernel/time/hrtimer.c:1880
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
__sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0x51/0xc0 arch/x86/kernel/apic/apic.c:1088
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:215
Code: 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 4c 07 05 0d 48 89 de 5b e9 73 b2 57 00 cc cc cc f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 10 46 7c 7e 65 8b 15 11 46 7c 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90000007640 EFLAGS: 00000286
RAX: ffffffff887f5506 RBX: ffff88802fbb6a00 RCX: 0000000000000100
RDX: ffff88802bdfbc00 RSI: 0000000000000000 RDI: ffff88802fbb6a00
RBP: 0000000000000000 R08: ffff88802fbb6a3f R09: 0000000000000000
R10: ffff88802fbb6a28 R11: ffffed1005f76d48 R12: 0000000000000000
R13: 0000000000000000 R14: 1ffff92000000f0c R15: dffffc0000000000
skb_ext_add+0x26/0x8e0 net/core/skbuff.c:6764
nf_bridge_alloc include/net/netfilter/br_netfilter.h:12 [inline]
br_nf_pre_routing_ipv6+0x136/0x6a0 net/bridge/br_netfilter_ipv6.c:172
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
br_handle_frame+0x1240/0x14d0 net/bridge/br_input.c:424
__netif_receive_skb_core+0xf94/0x3ab0 net/core/dev.c:5540
__netif_receive_skb_one_core net/core/dev.c:5644 [inline]
__netif_receive_skb+0x74/0x290 net/core/dev.c:5760
process_backlog+0x380/0x710 net/core/dev.c:6088
__napi_poll+0xbb/0x460 net/core/dev.c:6650
napi_poll net/core/dev.c:6717 [inline]
net_rx_action+0x65f/0xcc0 net/core/dev.c:6853
handle_softirqs+0x27d/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x267/0x8f0 kernel/sched/core.c:5256
Code: 31 09 85 c0 0f 84 30 01 00 00 48 85 db 0f 85 4f 01 00 00 0f 1f 44 00 00 4c 89 e7 e8 23 f7 3a 09 e8 be 19 30 00 fb 4c 8b 65 b8 <49> 8d bc 24 00 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc90019847500 EFLAGS: 00000286
RAX: 6cd3ec67e4fb9800 RBX: 0000000000000000 RCX: 6cd3ec67e4fb9800
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1d32e0
RBP: ffffc90019847550 R08: ffffffff911ed52f R09: 1ffffffff223daa5
R10: dffffc0000000000 R11: fffffbfff223daa6 R12: ffff88802bdfbc00
R13: 1ffff110171c79a9 R14: dffffc0000000000 R15: ffff8880b8e3cd48
context_switch kernel/sched/core.c:5385 [inline]
__schedule+0x15b6/0x4660 kernel/sched/core.c:6701
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7011
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:slab_update_freelist mm/slub.c:617 [inline]
RIP: 0010:__slab_free+0x22f/0x400 mm/slub.c:3682
Code: 75 33 48 89 f7 4c 89 d6 4c 89 ea 48 89 d9 4d 89 f8 e8 b5 de ff ff 41 89 c7 eb 55 4c 89 f9 4c 89 d0 4c 89 ea f0 48 0f c7 4e 20 <0f> 84 86 00 00 00 e9 9f fe ff ff 48 89 6c 24 08 48 89 f5 4c 89 64
RSP: 0018:ffffc900198478e0 EFLAGS: 00000242
RAX: ffff888059d8a200 RBX: ffff888059d89100 RCX: 0000000080070001
RDX: 0000000080070002 RSI: ffffea0001676200 RDI: 0000000000000000
RBP: ffff888019e5c780 R08: 0000000000000001 R09: 0000000000000000
R10: ffff888059d8a200 R11: fffffbfff223daa6 R12: ffff888019e5c780
R13: 0000000080070002 R14: 0000000080070001 R15: 0000000080070001
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
slab_alloc_node mm/slub.c:3495 [inline]
__kmem_cache_alloc_node+0x194/0x250 mm/slub.c:3534
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc_node+0xa6/0x240 mm/slab_common.c:1014
kmalloc_node include/linux/slab.h:620 [inline]
__vmalloc_area_node mm/vmalloc.c:3144 [inline]
__vmalloc_node_range+0x598/0x1320 mm/vmalloc.c:3339
__bpf_map_area_alloc kernel/bpf/syscall.c:309 [inline]
bpf_map_area_alloc+0xf1/0x110 kernel/bpf/syscall.c:316
reuseport_array_alloc+0x98/0x120 kernel/bpf/reuseport_array.c:155
map_create+0x877/0x12f0 kernel/bpf/syscall.c:1247
__sys_bpf+0x651/0x890 kernel/bpf/syscall.c:5460
__do_sys_bpf kernel/bpf/syscall.c:5582 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5580 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5580
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f87bf99e0d9
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:00007f87bdbf6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f87bfc26090 RCX: 00007f87bf99e0d9
RDX: 0000000000000050 RSI: 0000200000000300 RDI: 0000000000000000
RBP: 00007f87bfa35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f87bfc26128 R14: 00007f87bfc26090 R15: 00007ffebe50c0c8
</TASK>
net_ratelimit: 12064 callbacks suppressed
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
net_ratelimit: 24222 callbacks suppressed
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bond0 with own address as source address (addr:ca:bc:73:4c:fd:a7, vlan:0)
Struck through repros no longer work on HEAD.