rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P18257/1:b..l rcu: (detected by 1, t=10502 jiffies, g=137677, q=1274192 ncpus=2) task:syz.1.3412 state:R running task stack:25624 pid:18257 tgid:18256 ppid:15032 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 preempt_schedule_notrace+0x57/0x90 kernel/sched/core.c:7502 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 rcu_is_watching+0x7f/0xb0 kernel/rcu/tree.c:753 trace_lock_acquire include/trace/events/lock.h:23 [inline] lock_acquire+0x5f/0x350 kernel/locking/lockdep.c:5831 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 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5672 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4610 [inline] slab_alloc_node mm/slub.c:4939 [inline] kmem_cache_alloc_noprof+0x2b8/0x650 mm/slub.c:4946 __kernfs_new_node+0xe6/0x980 fs/kernfs/dir.c:665 kernfs_new_node+0xea/0x140 fs/kernfs/dir.c:751 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1050 sysfs_add_file_mode_ns+0x237/0x300 fs/sysfs/file.c:316 create_files fs/sysfs/group.c:82 [inline] internal_create_group+0x679/0x1180 fs/sysfs/group.c:189 internal_create_groups fs/sysfs/group.c:229 [inline] sysfs_create_groups+0x59/0x120 fs/sysfs/group.c:255 device_add_groups drivers/base/core.c:2907 [inline] device_add_attrs+0xde/0x600 drivers/base/core.c:2971 device_add+0x488/0xb80 drivers/base/core.c:3711 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2337 register_netdevice+0x1433/0x1eb0 net/core/dev.c:11439 __ip_tunnel_create+0x3e8/0x560 net/ipv4/ip_tunnel.c:268 ip_tunnel_init_net+0x2ea/0x810 net/ipv4/ip_tunnel.c:1150 ops_init+0x35d/0x5d0 net/core/net_namespace.c:137 setup_net+0x118/0x350 net/core/net_namespace.c:446 copy_net_ns+0x4f9/0x720 net/core/net_namespace.c:579 create_new_namespaces+0x3f0/0x6b0 kernel/nsproxy.c:132 unshare_nsproxy_namespaces+0x149/0x190 kernel/nsproxy.c:234 ksys_unshare+0x57d/0xa00 kernel/fork.c:3266 __do_sys_unshare kernel/fork.c:3340 [inline] __se_sys_unshare kernel/fork.c:3338 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3338 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff68459ce59 RSP: 002b:00007ff6853a5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007ff684815fa0 RCX: 00007ff68459ce59 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000066000080 RBP: 00007ff684632e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff684816038 R14: 00007ff684815fa0 R15: 00007ff68493fa48 rcu: rcu_preempt kthread starved for 3079 jiffies! g137677 f0x2 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:28056 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0x164/0x360 kernel/sched/core.c:7322 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 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 16848 Comm: kworker/R-bond5 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: 0x0 (bond5) RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:873 [inline] RIP: 0010:class_rcu_destructor include/linux/rcupdate.h:1183 [inline] RIP: 0010:unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709 Code: a4 0e 01 48 c7 c7 40 a3 c9 8b be 66 03 00 00 48 c7 c2 e0 a3 c9 8b e8 55 5f 2b 00 48 c7 c7 a0 9b 95 8e 4c 89 ee e8 d6 45 2b 00 01 f4 34 00 89 e8 48 83 c4 70 5b 41 5c 41 5d 41 5e 41 5f 5d e9 RSP: 0018:ffffc90000006f40 EFLAGS: 00000282 RAX: abd1344acdcdfe00 RBX: ffffc90000006ff8 RCX: 0000000000000102 RDX: ffffc90000007001 RSI: ffffffff8c293c80 RDI: ffffffff8c293c40 RBP: 1ffffffff218e501 R08: ffffc90000007fc0 R09: 0000000000000000 R10: ffffc90000007038 R11: fffff52000000e09 R12: ffffc90000000000 R13: ffffffff8176b21f R14: ffffc90000006fe8 R15: ffffc90000007fd0 FS: 0000000000000000(0000) GS:ffff88812525a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000031b030 CR3: 000000007cda2000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000000000000000f DR3: 0000000000000006 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: 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:2700 [inline] slab_free mm/slub.c:6310 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6437 nft_synproxy_eval_v4+0x383/0x530 net/netfilter/nft_synproxy.c:61 nft_synproxy_do_eval+0x335/0x550 net/netfilter/nft_synproxy.c:142 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x48d/0x1b10 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x360/0x4b0 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6206 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0xa34/0x1860 net/core/dev.c:6670 __napi_poll+0xaa/0x330 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7949 handle_softirqs+0x225/0x840 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:finish_task_switch+0x417/0xbc0 kernel/sched/core.c:5361 Code: 03 00 00 41 c7 84 24 20 0e 00 00 00 00 00 00 e9 1b 06 00 00 49 83 c4 48 4c 89 e7 e8 a3 2a 1b 0a e8 2e ab 39 00 fb 4c 8b 65 c8 <49> 8d bc 24 f8 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 RSP: 0018:ffffc9000528fa60 EFLAGS: 00000246 RAX: 0000000000000001 RBX: ffff8880b863bda0 RCX: 0000000080000002 RDX: 0000000000000000 RSI: ffffffff8c293c80 RDI: ffffffff8194c0f2 RBP: ffffc9000528fab0 R08: ffffffff903189f7 R09: 1ffffffff206313e R10: dffffc0000000000 R11: fffffbfff206313f R12: ffff888020708000 R13: ffff8880b863bd68 R14: dffffc0000000000 R15: 1ffff110170c77b4 context_switch kernel/sched/core.c:5507 [inline] __schedule+0x17e1/0x56c0 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0x164/0x360 kernel/sched/core.c:7322 rescuer_thread+0xf45/0x10b0 kernel/workqueue.c:3678 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 IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available IPVS: wrr: UDP 224.0.0.2:0 - no destination available NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5679 Comm: kworker/0:4 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_power_efficient neigh_periodic_work RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:101 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline] RIP: 0010:unwind_next_frame+0x4c3/0x2550 arch/x86/kernel/unwind_orc.c:510 Code: 01 4c 8b 6c 24 50 49 bc 00 00 00 00 00 fc ff df 4c 8b 7c 24 10 49 8d 6e 38 0f 84 8a 16 00 00 e9 ee 01 00 00 49 89 d5 49 89 d7 <4c> 89 e0 4c 29 f8 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 48 83 RSP: 0018:ffffc90000006920 EFLAGS: 00000246 RAX: ffffffff90a9a7a8 RBX: ffffffff90a9a7ac RCX: ffffffff90a9a7b0 RDX: ffffffff90a9a7a8 RSI: ffffffff9155242e RDI: ffffffff8c293c40 RBP: ffffffff8a12289e R08: 0000000000000003 R09: 0000000000000000 R10: ffffc90000006a18 R11: ffffffff81b127f0 R12: ffffffff90a9a7b0 R13: ffffffff90a9a7ac R14: ffffc900000069c8 R15: ffffffff90a9a7b0 FS: 0000000000000000(0000) GS:ffff88812525a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000031b030 CR3: 000000007cda2000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000000000000000f DR3: 0000000000000006 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: 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 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4610 [inline] slab_alloc_node mm/slub.c:4939 [inline] kmem_cache_alloc_noprof+0x2b8/0x650 mm/slub.c:4946 skb_clone+0x212/0x3a0 net/core/skbuff.c:2110 dev_queue_xmit_nit+0x28d/0xac0 net/core/dev.c:2575 xmit_one net/core/dev.c:3885 [inline] dev_hard_start_xmit+0x1c1/0x830 net/core/dev.c:3905 __dev_queue_xmit+0x1435/0x37f0 net/core/dev.c:4872 dev_queue_xmit include/linux/netdevice.h:3436 [inline] neigh_hh_output include/net/neighbour.h:544 [inline] neigh_output include/net/neighbour.h:558 [inline] ip_finish_output2+0xbda/0x10b0 net/ipv4/ip_output.c:236 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:437 synproxy_send_client_synack+0x89b/0xde0 net/netfilter/nf_synproxy_core.c:487 nft_synproxy_eval_v4+0x37b/0x530 net/netfilter/nft_synproxy.c:60 nft_synproxy_do_eval+0x335/0x550 net/netfilter/nft_synproxy.c:142 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x48d/0x1b10 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x360/0x4b0 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6206 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0xa34/0x1860 net/core/dev.c:6670 __napi_poll+0xaa/0x330 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7949 handle_softirqs+0x225/0x840 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:396 [inline] neigh_periodic_work+0xc23/0xe40 net/core/neighbour.c:1035 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