syzbot


INFO: rcu detected stall in br_handle_frame (2)

Status: upstream: reported on 2025/10/06 18:18
Reported-by: syzbot+f80e255c3d4ba8ded1e0@syzkaller.appspotmail.com
First crash: 195d, last: 9d00h
Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in br_handle_frame (5) bridge 1 syz 24 526d 554d 28/29 fixed on 2024/11/12 23:31
linux-4.14 INFO: rcu detected stall in br_handle_frame (3) 1 1 2027d 2027d 0/1 auto-closed as invalid on 2021/01/28 07:46
upstream INFO: rcu detected stall in br_handle_frame 1 C done 341 2408d 2413d 13/29 fixed on 2019/10/09 10:54
upstream INFO: rcu detected stall in br_handle_frame (2) net 1 C done 2 2312d 2308d 15/29 fixed on 2020/02/18 14:31
upstream INFO: rcu detected stall in br_handle_frame (3) bridge 1 1 1737d 1737d 0/29 auto-closed as invalid on 2021/10/15 13:41
linux-4.14 INFO: rcu detected stall in br_handle_frame (2) 1 C done 1 2313d 2313d 1/1 fixed on 2020/01/19 15:05
linux-4.14 INFO: rcu detected stall in br_handle_frame 1 C done 15 2405d 2417d 1/1 fixed on 2019/12/07 19:24
linux-4.19 INFO: rcu detected stall in br_handle_frame (2) 1 C error 31 1172d 2013d 0/1 upstream: reported C repro on 2020/10/14 18:56
linux-4.19 INFO: rcu detected stall in br_handle_frame 1 C done 41 2405d 2417d 1/1 fixed on 2019/12/07 19:18
linux-5.15 INFO: rcu detected stall in br_handle_frame 1 C inconclusive 3 151d 801d 0/3 upstream: reported C repro on 2024/02/08 13:52
upstream INFO: rcu detected stall in br_handle_frame (6) bridge 1 C error error 62 30d 96d 0/29 upstream: reported C repro on 2026/01/13 18:06
linux-6.1 INFO: rcu detected stall in br_handle_frame 1 2 601d 683d 0/3 auto-obsoleted due to no activity on 2024/12/04 21:21
upstream INFO: rcu detected stall in br_handle_frame (4) kernel 1 1 1576d 1576d 0/29 closed as invalid on 2022/02/08 10:10
linux-6.6 INFO: rcu detected stall in br_handle_frame 1 14 4d10h 150d 0/2 upstream: reported on 2025/11/21 04:49
android-5-15 BUG: soft lockup in br_handle_frame 1 2 610d 615d 0/2 auto-obsoleted due to no activity on 2024/11/16 05:31

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P2039 0-.... } 2653 jiffies s: 133437 root: 0x1/T
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 20238 Comm: syz.7.3550 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:__pvclock_read_cycles arch/x86/include/asm/pvclock.h:84 [inline]
RIP: 0010:pvclock_clocksource_read+0xf9/0x760 arch/x86/kernel/pvclock.c:76
Code: 0f 85 45 01 00 00 43 0f b6 04 26 84 c0 0f 85 7f 01 00 00 8b 1f 0f 01 f9 66 90 48 89 d5 48 8b 8c 24 90 00 00 00 42 0f b6 0c 21 <84> c9 0f 85 a6 01 00 00 48 8b 8c 24 88 00 00 00 42 0f b6 0c 21 84
RSP: 0018:ffffc90000006e00 EFLAGS: 00000046
RAX: 00000000c0456d66 RBX: 0000000000000010 RCX: 0000000000000000
RDX: 000000000000036d RSI: ffffffff8fa0c01c RDI: ffffffff8fa0c000
RBP: 000000000000036d R08: ffffffff8fa0c008 R09: ffffffff8fa0c018
R10: ffffffff8fa0c010 R11: ffffffff8fa0c003 R12: dffffc0000000000
R13: ffff88804f2e3198 R14: 1ffffffff1f41800 R15: 0000000000000001
FS:  00007f633bab66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f633ba94ff8 CR3: 000000005327b000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 kvm_clock_read arch/x86/kernel/kvmclock.c:79 [inline]
 kvm_sched_clock_read+0x14/0x40 arch/x86/kernel/kvmclock.c:91
 __bpf_prog_run include/linux/filter.h:593 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 bpf_prog_run_array include/linux/bpf.h:1668 [inline]
 trace_call_bpf+0x36b/0x6b0 kernel/trace/bpf_trace.c:135
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
 perf_trace_lock+0x301/0x390 include/trace/events/lock.h:50
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0x8ad/0x920 kernel/locking/lockdep.c:5673
 seqcount_lockdep_reader_access+0xe0/0x1d0 include/linux/seqlock.h:103
 ktime_get_update_offsets_now+0x44/0x3e0 kernel/time/timekeeping.c:2317
 hrtimer_update_base kernel/time/hrtimer.c:659 [inline]
 hrtimer_interrupt+0x130/0x9c0 kernel/time/hrtimer.c:1855
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:check_preemption_disabled+0x13/0x110 lib/smp_processor_id.c:13
Code: 00 cc cc 00 00 cc cc 48 c7 c7 c0 0c df 8a 48 c7 c6 00 0d df 8a eb 00 55 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 <48> 89 44 24 08 65 8b 05 b1 3f d4 75 65 8b 0d 52 95 d4 75 f7 c1 ff
RSP: 0018:ffffc900000075b0 EFLAGS: 00000282
RAX: c76ecc547b97ff00 RBX: 0000000000000000 RCX: 0000000000000101
RDX: ffff8880279bbb80 RSI: ffffffff8adf0d00 RDI: ffffffff8adf0cc0
RBP: 0000000000000001 R08: ffffffff8e1fdeef R09: 1ffffffff1c3fbdd
R10: dffffc0000000000 R11: fffffbfff1c3fbde R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88807bdf6800 R15: ffff888059eeaa00
 rcu_lockdep_current_cpu_online+0x33/0x120 kernel/rcu/tree.c:768
 rcu_read_lock_held_common kernel/rcu/update.c:112 [inline]
 rcu_read_lock_held+0x1a/0x40 kernel/rcu/update.c:309
 br_port_get_rcu net/bridge/br_private.h:429 [inline]
 bridge_parent net/bridge/br_netfilter_hooks.c:159 [inline]
 brnf_get_logical_dev+0x6c/0x2c0 net/bridge/br_netfilter_hooks.c:459
 setup_pre_routing+0x1cb/0x460 net/bridge/br_netfilter_hooks.c:482
 br_nf_pre_routing_ipv6+0x169/0x6b0 net/bridge/br_netfilter_ipv6.c:234
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:260 [inline]
 br_handle_frame+0x1167/0x13c0 net/bridge/br_input.c:406
 __netif_receive_skb_core+0x1004/0x38f0 net/core/dev.c:5501
 __netif_receive_skb_one_core net/core/dev.c:5605 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5721
 process_backlog+0x38d/0x6f0 net/core/dev.c:6049
 __napi_poll+0xc0/0x460 net/core/dev.c:6616
 napi_poll net/core/dev.c:6683 [inline]
 net_rx_action+0x5dd/0xb20 net/core/dev.c:6797
 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_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x9d/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5124
Code: 0f 84 3b 01 00 00 48 85 db 0f 85 5a 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 00 2c de 08 e8 8b 2c 2f 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90003ef7058 EFLAGS: 00000282
RAX: c76ecc547b97ff00 RBX: 0000000000000000 RCX: c76ecc547b97ff00
RDX: dffffc0000000000 RSI: ffffffff8a8c10a0 RDI: ffffffff8adf0d20
RBP: ffffc90003ef70b0 R08: ffff8880b8e3ab03 R09: 1ffff110171c7560
R10: dffffc0000000000 R11: ffffed10171c7561 R12: ffff8880279bbb80
R13: dffffc0000000000 R14: ffff88802a250000 R15: ffff8880b8e3b5d0
 context_switch kernel/sched/core.c:5248 [inline]
 __schedule+0x11d9/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6731
 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6755
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x10d/0x120 kernel/locking/spinlock.c:194
 __debug_check_no_obj_freed lib/debugobjects.c:988 [inline]
 debug_check_no_obj_freed+0x515/0x530 lib/debugobjects.c:1009
 free_pages_prepare mm/page_alloc.c:1492 [inline]
 free_pcp_prepare mm/page_alloc.c:1536 [inline]
 free_unref_page_prepare+0x2a6/0x9a0 mm/page_alloc.c:3413
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3508
 free_slab mm/slub.c:2036 [inline]
 discard_slab mm/slub.c:2042 [inline]
 __unfreeze_partials+0x1a5/0x200 mm/slub.c:2591
 put_cpu_partial+0x17c/0x250 mm/slub.c:2667
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 kmem_cache_alloc_node+0x14d/0x320 mm/slub.c:3404
 alloc_vmap_area+0x18e/0x18c0 mm/vmalloc.c:1619
 __get_vm_area_node+0x158/0x330 mm/vmalloc.c:2513
 __vmalloc_node_range+0x357/0x13b0 mm/vmalloc.c:3203
 __vmalloc_node mm/vmalloc.c:3308 [inline]
 __vmalloc+0x76/0x80 mm/vmalloc.c:3322
 bpf_prog_alloc_no_stats+0x3a/0x3a0 kernel/bpf/core.c:92
 bpf_prog_alloc+0x1c/0x1b0 kernel/bpf/core.c:130
 bpf_prog_load+0x7c9/0x1560 kernel/bpf/syscall.c:2597
 __sys_bpf+0x5b8/0x780 kernel/bpf/syscall.c:5031
 __do_sys_bpf kernel/bpf/syscall.c:5135 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5133 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5133
 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: 0033:0x7f633ab9c819
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:00007f633bab6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f633ae16090 RCX: 00007f633ab9c819
RDX: 0000000000000052 RSI: 000020000000e000 RDI: 0000000000000005
RBP: 00007f633ac32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f633ae16128 R14: 00007f633ae16090 R15: 00007ffc96ee9bc8
 </TASK>
net_ratelimit: 6790 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 16266 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:ce:f5:c0:3d:93:8f, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/11 06:54 linux-6.1.y 1989cd3d56e2 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in br_handle_frame
2026/01/28 17:06 linux-6.1.y cd9b81672742 004c195c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in br_handle_frame
2026/01/25 14:09 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in br_handle_frame
2025/12/08 16:59 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in br_handle_frame
2025/10/06 18:17 linux-6.1.y 882efbdd9d34 91305dbe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in br_handle_frame
* Struck through repros no longer work on HEAD.