rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P24617/1:b..l rcu: (detected by 1, t=10503 jiffies, g=312001, q=395188 ncpus=2) task:syz.5.5910 state:R running task stack:25896 pid:24617 tgid:24617 ppid:19834 task_flags:0x40044c flags:0x00080003 Call Trace: 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:__preempt_count_add kernel/rcu/tree.c:748 [inline] RIP: 0010:rcu_is_watching+0x4/0xb0 kernel/rcu/tree.c:751 Code: b5 8e e8 ff 78 64 03 eb cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <41> 57 41 56 53 65 ff 05 a0 5f c1 11 e8 6b 71 25 0a 89 c3 83 f8 08 RSP: 0018:ffffc9000558f760 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88802e045d00 RDX: 0000000000000000 RSI: ffffffff823e99ce RDI: ffffffff8eb59c60 RBP: ffff8881414a7344 R08: ffff8881414a7307 R09: 1ffff11028294e60 R10: dffffc0000000000 R11: ffffed1028294e61 R12: ffff88802e046344 R13: ffffffff823e99ce R14: ffffffff8eb59c60 R15: 0000000000000001 trace_lock_release include/trace/events/lock.h:68 [inline] lock_release+0x4b/0x3c0 kernel/locking/lockdep.c:5879 rcu_lock_release include/linux/rcupdate.h:310 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] __update_page_owner_free_handle+0x466/0x4a0 mm/page_owner.c:295 __reset_page_owner+0x85/0x1f0 mm/page_owner.c:321 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] free_pages_prepare+0x960/0xa60 mm/page_alloc.c:1451 __free_contig_range_common+0x174/0x340 mm/page_alloc.c:6897 __free_contig_range mm/page_alloc.c:6942 [inline] free_pages_bulk+0x48/0x120 mm/page_alloc.c:5257 vm_area_free_pages mm/vmalloc.c:3439 [inline] vfree+0x224/0x4a0 mm/vmalloc.c:3488 kcov_put kernel/kcov.c:449 [inline] kcov_close+0x28/0x50 kernel/kcov.c:554 __fput+0x418/0xa50 fs/file_table.c:512 task_work_run+0x1d9/0x270 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x73a/0x2360 kernel/exit.c:1009 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: 0033:0x5 RSP: 002b:00007f4bee1a3f58 EFLAGS: 00000246 ORIG_RAX: 18e753b331ef2848 RAX: d6b2c6cf9d780a25 RBX: 8c17fa9c8c87e200 RCX: f1521e6d02b596a6 RDX: 53f3a01d6d567492 RSI: 5e1cf7eb30e365dd RDI: 7276fdc553273f82 RBP: 81ee7639cb75b6fa R08: 0b4549c7e58b697d R09: b8ef3dd68d02d45a R10: 22dc2419b4d49ef3 R11: 3da9ed46b00e13ac R12: 6cb3d1a8d7b5a220 R13: d9bc8edbf29d588f R14: 9b8908dcbb4f02b4 R15: 107b9d1451766018 rcu: rcu_preempt kthread starved for 498 jiffies! g312001 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: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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 24296 Comm: kworker/u8:33 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker RIP: 0010:synproxy_send_client_synack_ipv6+0x484/0xcd0 net/netfilter/nf_synproxy_core.c:894 Code: 85 c6 05 00 00 48 8d 94 24 a0 00 00 00 41 0f b7 1c 24 49 8d 7e 02 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 c3 05 00 00 <66> 41 89 5e 02 48 89 f7 4c 89 e6 e8 1c f9 92 00 0f c8 4d 8d 7e 04 RSP: 0018:ffffc900000072e0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000200 RCX: ffff88806d265d00 RDX: ffffc90000007380 RSI: ffff8881ef305800 RDI: ffff8881ef3054ea RBP: ffffc900000073f0 R08: 0000000000000000 R09: 0100000000000000 R10: 0000000000000000 R11: 0100000000000000 R12: ffff8881ef305828 R13: dffffc0000000000 R14: ffff8881ef3054e8 R15: ffff8881ef30582a FS: 0000000000000000(0000) GS:ffff888124f4b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe5a5600218 CR3: 000000000e946000 CR4: 00000000003526f0 Call Trace: nft_synproxy_eval_v6+0x362/0x4e0 net/netfilter/nft_synproxy.c:90 nft_synproxy_do_eval+0x3d1/0x550 net/netfilter/nft_synproxy.c:145 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 ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:545 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6212 [inline] __netif_receive_skb net/core/dev.c:6325 [inline] process_backlog+0x774/0x1860 net/core/dev.c:6676 __napi_poll+0xaa/0x330 net/core/dev.c:7735 napi_poll net/core/dev.c:7798 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7955 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 blake2s_compress+0xfa/0x1c00 lib/crypto/x86/blake2s.h:42 blake2s_update+0x140/0x450 lib/crypto/blake2s.c:119 hmac+0x2d1/0x3b0 drivers/net/wireguard/noise.c:332 kdf+0x12d/0x290 drivers/net/wireguard/noise.c:367 mix_dh drivers/net/wireguard/noise.c:413 [inline] wg_noise_handshake_create_initiation+0x29e/0x810 drivers/net/wireguard/noise.c:550 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:34 [inline] wg_packet_handshake_send_worker+0x18c/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