INFO: rcu detected stall in ipv6_list_rcv (5)

Status: auto-obsoleted due to no activity on 2026/10/25 07:03
Subsystems: netfilter
Labels: prio:normal
[Documentation on labels]
First crash: 92d, last: 92d
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ID Workflow Result Correct Bug Created Started Finished Revision
7a6a7c37 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in ipv6_list_rcv (5) 2026/07/29 02:39 2026/07/29 02:39 2026/07/29 03:26 7be3c40b
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in ipv6_list_rcv (2) 1 1 205d 205d 0/3 auto-obsoleted due to no activity on 2026/07/14 06:20
upstream INFO: rcu detected stall in ipv6_list_rcv (3) net 1 6 675d 881d 0/29 auto-obsoleted due to no activity on 2025/03/20 19:56
linux-6.6 INFO: rcu detected stall in ipv6_list_rcv 1 1 144d 144d 0/2 auto-obsoleted due to no activity on 2026/09/12 21:34
linux-6.1 INFO: rcu detected stall in ipv6_list_rcv 1 2 598d 601d 0/3 auto-obsoleted due to no activity on 2025/06/16 07:00
upstream INFO: rcu detected stall in ipv6_list_rcv (2) net 1 1 1847d 1847d 0/29 auto-closed as invalid on 2021/12/05 01:49
upstream INFO: rcu detected stall in ipv6_list_rcv trace 1 2 2148d 2149d 0/29 auto-closed as invalid on 2021/03/09 05:51

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=92cc/1/0x4000000000000000 softirq=15227/15228 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3327/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=15305, q=2136 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5754 Comm: kworker/1:4 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: mld mld_ifc_work
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:118 [inline]
RIP: 0010:lock_release+0x5a/0x3c0 kernel/locking/lockdep.c:5881
Code: 11 83 f8 08 0f 83 56 02 00 00 89 c0 48 0f a3 05 4c a5 b4 0e 73 0d e8 25 f9 08 00 84 c0 0f 84 94 02 00 00 83 3d 46 d8 b4 0e 00 <0f> 84 1c 02 00 00 65 8b 05 e9 5f ca 11 85 c0 0f 85 0d 02 00 00 65
RSP: 0018:ffffc90000a08360 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffff8880333092a8 RCX: 0000000000010103
RDX: 0000000000010100 RSI: ffffffff8c4bdb60 RDI: ffffffff8c4bdb20
RBP: ffff88807ad57000 R08: ffff88807ad57083 R09: 1ffff1100f5aae10
R10: dffffc0000000000 R11: ffffed100f5aae11 R12: ffff88807ad57000
R13: ffffffff89ddd9ba R14: ffff8880333092c0 R15: ffff888033309300
FS:  0000000000000000(0000) GS:ffff888125050000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fccc4fec000 CR3: 000000000e946000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __raw_spin_unlock include/linux/spinlock_api_smp.h:167 [inline]
 _raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:190
 spin_unlock include/linux/spinlock.h:390 [inline]
 advance_sched+0x99a/0xc80 net/sched/sch_taprio.c:988
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x3bc/0xa10 kernel/time/hrtimer.c:2096
 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:nf_nat_ipv6_in+0x0/0x2c0 net/netfilter/nf_nat_proto.c:939
Code: 80 e1 07 fe c1 38 c1 0f 8c 51 fe ff ff 4c 89 f7 e8 25 53 3a f8 e9 44 fe ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48
RSP: 0018:ffffc90000a08788 EFLAGS: 00000246
RAX: 1ffff1100f0cfc88 RBX: ffffffff89fa4110 RCX: ffff888029ca5d00
RDX: ffffc90000a08980 RSI: ffff888032dd5dc0 RDI: ffff88802bf577c0
RBP: dffffc0000000000 R08: ffff888029ca5d00 R09: 0000000000000004
R10: 0000000000000003 R11: ffffffff89fa4110 R12: 0000000000000003
R13: ffff88807867e438 R14: 1ffff1100f0cfc80 R15: ffff88807867e440
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
 nf_hook_slow_list+0x1d0/0x3a0 net/netfilter/core.c:656
 NF_HOOK_LIST include/linux/netfilter.h:354 [inline]
 ip6_sublist_rcv+0xc5d/0xd70 net/ipv6/ip6_input.c:359
 ipv6_list_rcv+0x3ef/0x440 net/ipv6/ip6_input.c:395
 __netif_receive_skb_list_ptype net/core/dev.c:6255 [inline]
 __netif_receive_skb_list_core+0x5ff/0x830 net/core/dev.c:6302
 __netif_receive_skb_list net/core/dev.c:6354 [inline]
 netif_receive_skb_list_internal+0x995/0xcf0 net/core/dev.c:6445
 netif_receive_skb_list+0x67/0x480 net/core/dev.c:6497
 ieee80211_rx_napi+0x37f/0x3d0 net/mac80211/rx.c:5747
 ieee80211_rx include/net/mac80211.h:5437 [inline]
 ieee80211_handle_queued_frames+0xe4/0x1d0 net/mac80211/main.c:452
 tasklet_action_common+0x2d7/0x490 kernel/softirq.c:938
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 do_softirq+0x76/0xd0 kernel/softirq.c:523
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:914 [inline]
 __dev_queue_xmit+0x1edc/0x3820 net/core/dev.c:4913
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip6_output+0x337/0x540 net/ipv6/ip6_output.c:246
 dst_output include/net/dst.h:471 [inline]
 NF_HOOK+0x177/0x4f0 include/linux/netfilter.h:318
 mld_sendpack+0x890/0xe10 net/ipv6/mcast.c:1869
 mld_send_cr net/ipv6/mcast.c:2170 [inline]
 mld_ifc_work+0x842/0xd60 net/ipv6/mcast.c:2710
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:kworker/u8:10   state:R  running task     stack:25064 pid:3327  tgid:3327  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound macvlan_process_broadcast
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 61 4f 2e 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 4b 4a ca 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 38 63 b8
RSP: 0018:ffffc9000e287420 EFLAGS: 00000282
RAX: e851248c6e796f00 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 0000000095d5e0c0 RSI: ffffffff8e4b1e80 RDI: ffffffff8c4bdb80
RBP: ffffffff8177827f R08: ffffffff8177827f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000002
R13: ffffffff8eb59c60 R14: 0000000000000000 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:840 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2705 [inline]
 slab_free mm/slub.c:6405 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6720
 skb_kfree_head net/core/skbuff.c:1083 [inline]
 skb_free_head net/core/skbuff.c:1095 [inline]
 skb_release_data+0x85e/0xab0 net/core/skbuff.c:1122
 skb_release_all net/core/skbuff.c:1197 [inline]
 __kfree_skb+0x5d/0x210 net/core/skbuff.c:1211
 macvlan_process_broadcast+0x550/0x660 drivers/net/macvlan.c:349
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g15305 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:27496 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7326
 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5620 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x10b0/0x14b0 kernel/smp.c:892
Code: c0 75 73 41 8b 1e 89 de 83 e6 01 31 ff e8 d8 22 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 84 1e 0c 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 69 1e 0c
RSP: 0018:ffffc90003cbf460 EFLAGS: 00000293
RAX: ffffffff81bae317 RBX: dffffc0000000000 RCX: ffff88807a7e1f00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003cbf588 R08: ffffffff90578a37 R09: 1ffffffff20af146
R10: dffffc0000000000 R11: fffffbfff20af147 R12: 1ffff110170e81d1
R13: ffff8880b863c448 R14: ffff8880b8740e88 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888124f50000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000559400090db8 CR3: 000000000e946000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x5c4/0x1090 arch/x86/mm/tlb.c:1451
 tlb_flush arch/x86/include/asm/tlb.h:23 [inline]
 tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline]
 tlb_flush_mmu+0x1af/0xa30 mm/mmu_gather.c:423
 tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:549
 free_ldt_pgtables+0x192/0x360 arch/x86/kernel/ldt.c:411
 arch_exit_mmap arch/x86/include/asm/mmu_context.h:229 [inline]
 exit_mmap+0x1bf/0x9f0 mm/mmap.c:1285
 __mmput+0x118/0x420 kernel/fork.c:1187
 exit_mm+0x221/0x2d0 kernel/exit.c:615
 do_exit+0x6cd/0x2360 kernel/exit.c:997
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 get_signal+0x121b/0x12c0 kernel/signal.c:3046
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fccc4d59017
Code: Unable to access opcode bytes at 0x7fccc4d58fed.
RSP: 002b:00007ffe3fb81b70 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 000055556114f500 RCX: 00007fccc4d59017
RDX: 0000000040000000 RSI: 00007ffe3fb81bcc RDI: ffffffffffffffff
RBP: 00007ffe3fb81bcc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffe3fb81e28 R15: 0000000000000000
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/27 07:03 net 53658c6f3682 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in ipv6_list_rcv
* Struck through repros no longer work on HEAD.