rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4962/1:b..l rcu: (detected by 0, t=10503 jiffies, g=27577, q=822 ncpus=2) task:klogd state:R running task stack:23376 pid:4962 tgid:4962 ppid:1 task_flags:0x400100 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 preempt_schedule_notrace+0x57/0x90 kernel/sched/core.c:7506 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 rcu_is_watching+0x7f/0xb0 kernel/rcu/tree.c:753 rcu_read_unlock include/linux/rcupdate.h:869 [inline] class_rcu_destructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0x1b66/0x2550 arch/x86/kernel/unwind_orc.c:709 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:1406 [inline] __free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950 __slab_free+0x274/0x2c0 mm/slub.c:5741 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:4584 [inline] slab_alloc_node mm/slub.c:4917 [inline] __do_kmalloc_node mm/slub.c:5333 [inline] __kmalloc_node_track_caller_noprof+0x461/0x730 mm/slub.c:5471 kmalloc_reserve net/core/skbuff.c:637 [inline] __alloc_skb+0x2bd/0x7a0 net/core/skbuff.c:715 alloc_skb include/linux/skbuff.h:1384 [inline] alloc_skb_with_frags+0xc6/0x760 net/core/skbuff.c:6775 sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:3012 unix_dgram_sendmsg+0x4da/0x17b0 net/unix/af_unix.c:2137 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775 __sock_sendmsg net/socket.c:790 [inline] __sys_sendto+0x408/0x5a0 net/socket.c:2252 __do_sys_sendto net/socket.c:2259 [inline] __se_sys_sendto net/socket.c:2255 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2255 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: 0033:0x7f6c95c0d407 RSP: 002b:00007ffe53b10a60 EFLAGS: 00000202 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f6c95abdc80 RCX: 00007f6c95c0d407 RDX: 0000000000000097 RSI: 00007ffe53b10ba0 RDI: 0000000000000003 RBP: 00007ffe53b10fd0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffe53b10fe8 R13: 00007ffe53b10ba0 R14: 000000000000007c R15: 00007ffe53b10ba0 rcu: rcu_preempt kthread starved for 10535 jiffies! g27577 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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: 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 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 62 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline] RIP: 0010:raw_atomic_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:2170 [inline] RIP: 0010:atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1302 [inline] RIP: 0010:queued_spin_lock include/asm-generic/qspinlock.h:111 [inline] RIP: 0010:do_raw_spin_lock+0x138/0x2f0 kernel/locking/spinlock_debug.c:116 Code: df be 04 00 00 00 49 89 d6 e8 64 45 91 00 48 8d 7c 24 40 be 04 00 00 00 e8 55 45 91 00 8b 44 24 40 b9 01 00 00 00 f0 0f b1 0b <0f> 85 20 01 00 00 43 c6 44 34 04 f8 65 8b 1d 19 27 c9 11 43 0f b6 RSP: 0018:ffffc90000a07d40 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff8880b87281c0 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000a07d80 RBP: ffffc90000a07df0 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000140fb0 R12: 1ffff92000140fac R13: ffff8880b87281c8 R14: dffffc0000000000 R15: 1ffff110170e5039 FS: 0000000000000000(0000) GS:ffff888125058000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4cbdee2c11 CR3: 000000000e946000 CR4: 00000000003526f0 Call Trace: __run_hrtimer kernel/time/hrtimer.c:2036 [inline] __hrtimer_run_queues+0x466/0xa10 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:rt6_score_route+0x31c/0x380 net/ipv6/route.c:771 Code: 8a b6 26 f7 e8 55 65 30 f7 bf ff ff ff ff 89 ee e8 39 d6 4a f7 85 ed 78 07 e8 f0 d1 4a f7 eb 07 e8 e9 d1 4a f7 89 eb 89 d8 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 e1 80 e1 07 80 RSP: 0018:ffffc90000a080e8 EFLAGS: 00000246 RAX: 00000000fffffffd RBX: ffff888058d34cc8 RCX: ffff88801c349f00 RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000003 R08: ffffc90000a08420 R09: ffffc90000a08430 R10: ffffc90000a08280 R11: fffff52000141052 R12: 0000000000000000 R13: dffffc0000000000 R14: ffff888058d34cc8 R15: 0000000000000001 find_match+0x119/0xb40 net/ipv6/route.c:788 __find_rr_leaf+0x243/0x740 net/ipv6/route.c:872 find_rr_leaf net/ipv6/route.c:893 [inline] rt6_select net/ipv6/route.c:937 [inline] fib6_table_lookup+0x3c6/0xae0 net/ipv6/route.c:2255 ip6_pol_route+0x229/0x14d0 net/ipv6/route.c:2292 pol_lookup_func include/net/ip6_fib.h:669 [inline] __fib6_rule_action net/ipv6/fib6_rules.c:240 [inline] fib6_rule_action+0x9d7/0xc00 net/ipv6/fib6_rules.c:278 fib_rules_lookup+0x770/0xeb0 net/core/fib_rules.c:338 fib6_rule_lookup+0x1a0/0x730 net/ipv6/fib6_rules.c:115 ip6_route_input_lookup net/ipv6/route.c:2363 [inline] ip6_route_input+0x78d/0xb20 net/ipv6/route.c:2666 ip6_rcv_finish+0x141/0x280 net/ipv6/ip6_input.c:117 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:325 __netif_receive_skb_one_core net/core/dev.c:6241 [inline] __netif_receive_skb net/core/dev.c:6354 [inline] process_backlog+0x774/0x1860 net/core/dev.c:6705 __napi_poll+0xaa/0x330 net/core/dev.c:7764 napi_poll net/core/dev.c:7827 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7984 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 local_bh_enable include/linux/bottom_half.h:33 [inline] __alloc_skb+0x1ad/0x7a0 net/core/skbuff.c:699 alloc_skb include/linux/skbuff.h:1384 [inline] wg_socket_send_buffer_to_peer+0x38/0x1c0 drivers/net/wireguard/socket.c:191 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0x204/0x370 drivers/net/wireguard/send.c:51 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 net_ratelimit: 3804 callbacks suppressed bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0) net_ratelimit: 3651 callbacks suppressed bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0) bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)