rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P8338/1:b..l rcu: (detected by 1, t=10503 jiffies, g=28405, q=920883 ncpus=2) task:syz.0.638 state:R running task stack:28056 pid:8338 tgid:8330 ppid:5641 task_flags:0x400040 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8b0 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:58 [inline] RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:409 [inline] RIP: 0010:deref_stack_reg+0xab/0x230 arch/x86/kernel/unwind_orc.c:419 Code: 4c 89 74 24 08 4d 8b 77 10 4c 89 fd 48 c1 ed 03 0f b6 44 35 00 84 c0 0f 85 3c 01 00 00 41 83 3f 00 0f 95 c0 4c 39 c3 0f 96 c1 <20> c1 4d 39 c6 0f 97 c0 20 c8 3c 01 75 18 49 8d 40 08 48 39 d8 0f RSP: 0018:ffffc90003b8f520 EFLAGS: 00000293 RAX: 0000000000000001 RBX: ffffc90003b88000 RCX: 0000000000000001 RDX: ffffc90003b8f688 RSI: dffffc0000000000 RDI: ffffc90003b8f648 RBP: 1ffff92000771ec9 R08: ffffc90003b8fea8 R09: 0000000000000000 R10: ffffc90003b8f698 R11: fffff52000771ed5 R12: 1ffff92000771eca R13: 1ffff92000771ecb R14: ffffc90003b90000 R15: ffffc90003b8f648 unwind_next_frame+0x19d5/0x2550 arch/x86/kernel/unwind_orc.c:-1 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+0xc1c/0xd30 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5613 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_kmalloc+0x22/0xb0 mm/kasan/common.c:406 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5296 [inline] __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] tomoyo_encode2 security/tomoyo/realpath.c:45 [inline] tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80 tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_number_perm+0x246/0x630 security/tomoyo/file.c:728 security_file_ioctl+0xc3/0x2a0 security/security.c:2512 __do_sys_ioctl fs/ioctl.c:591 [inline] __se_sys_ioctl+0x47/0x170 fs/ioctl.c:583 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: 0033:0x7f526839caeb RSP: 002b:00007f5269261050 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f5268616128 RCX: 00007f526839caeb RDX: 0000000000000000 RSI: 0000000000006364 RDI: 00000000000000d9 RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f52692616c0 R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000001 R13: 00007f5268616128 R14: 00007ffc73cc9020 R15: 00007ffc73cc9108 rcu: rcu_preempt kthread starved for 217 jiffies! g28405 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:27544 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0x164/0x360 kernel/sched/core.c:7283 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x389/0x470 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: 139 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker RIP: 0010:nf_nat_ipv4_fn net/netfilter/nf_nat_proto.c:583 [inline] RIP: 0010:nf_nat_ipv4_local_fn+0x336/0x540 net/netfilter/nf_nat_proto.c:738 Code: 41 0f b6 0c 24 4c 89 f7 48 89 ee 44 89 ea e8 21 cd ff ff eb 20 e8 4a e2 f2 f7 4c 8b 34 24 eb 05 e8 3f e2 f2 f7 48 8b 7c 24 10 <4c> 89 f6 4c 89 e2 e8 3f 87 ff ff 89 c5 49 bd 00 00 00 00 00 fc ff RSP: 0018:ffffc90000007060 EFLAGS: 00000246 RAX: ffffffff89d2d471 RBX: ffff8880aec037e8 RCX: ffff88801f7c9f00 RDX: 0000000000000100 RSI: ffffffff8fe5b8b0 RDI: ffff888078a62400 RBP: ffff88805bf46300 R08: ffff88801f7c9f00 R09: 0000000000000002 R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90000007160 R13: 0000000000000003 R14: ffff8880aec03780 R15: 1ffff11015d806fd FS: 0000000000000000(0000) GS:ffff8881252a0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fba9afeb078 CR3: 000000000e74a000 CR4: 00000000003526f0 Call Trace: nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273 __ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120 ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129 synproxy_send_client_synack+0x8c1/0xe30 net/netfilter/nf_synproxy_core.c:489 nft_synproxy_eval_v4+0x34a/0x4e0 net/netfilter/nft_synproxy.c:60 nft_synproxy_do_eval+0x305/0x580 net/netfilter/nft_synproxy.c:142 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x48d/0x1ae0 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:6202 [inline] __netif_receive_skb net/core/dev.c:6315 [inline] process_backlog+0xaa3/0x1950 net/core/dev.c:6666 __napi_poll+0xae/0x340 net/core/dev.c:7733 napi_poll net/core/dev.c:7796 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7953 handle_softirqs+0x22a/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+0xf9/0x1eb0 lib/crypto/x86/blake2s.h:42 blake2s_update+0x1cb/0x450 lib/crypto/blake2s.c:127 blake2s include/crypto/blake2s.h:156 [inline] compute_mac1+0x177/0x200 drivers/net/wireguard/cookie.c:80 wg_cookie_add_mac_to_packet+0x57/0x1a0 drivers/net/wireguard/cookie.c:163 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:35 [inline] wg_packet_handshake_send_worker+0x1aa/0x350 drivers/net/wireguard/send.c:51 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478 kthread+0x389/0x470 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