rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=183313, q=1122292 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 779 (4295034542-4295033763), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 780 jiffies! g183313 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: 5288 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:-1 [inline] RIP: 0010:rcu_is_watching+0x44/0xb0 kernel/rcu/tree.c:752 Code: 73 65 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd d0 b7 4f 8e 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 2c b6 88 00 <48> c7 c3 d8 38 6e 93 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 RSP: 0018:ffffc90000006c80 EFLAGS: 00000246 RAX: 1ffffffff1c9f6fa RBX: 0000000000000000 RCX: 0000000000000101 RDX: ffff888030889f00 RSI: ffffffff8c4bdb60 RDI: ffffffff8c4bdb20 RBP: ffffc90000006db0 R08: ffffffff89b8ea29 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: dffffc0000000000 R13: ffff888046dc9300 R14: ffffffff8e4fb7d0 R15: dffffc0000000000 FS: 00007fcff88cf780(0000) GS:ffff888124f50000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055d5a48f74b0 CR3: 00000000297b8000 CR4: 00000000003526f0 Call Trace: rcu_read_lock include/linux/rcupdate.h:841 [inline] fib_rules_lookup+0xd8/0xeb0 net/core/fib_rules.c:319 __fib_lookup+0x106/0x210 net/ipv4/fib_rules.c:96 ip_route_output_key_hash_rcu+0x294/0x2720 net/ipv4/route.c:2811 ip_route_output_key_hash+0x18d/0x2a0 net/ipv4/route.c:2702 __ip_route_output_key include/net/route.h:169 [inline] ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2929 ip_route_output_key include/net/route.h:179 [inline] ip_route_me_harder+0x762/0xfe0 net/ipv4/netfilter.c:54 synproxy_send_tcp+0x347/0x670 net/netfilter/nf_synproxy_core.c:434 synproxy_send_client_synack+0x89b/0xde0 net/netfilter/nf_synproxy_core.c:487 nft_synproxy_eval_v4+0x362/0x4e0 net/netfilter/nft_synproxy.c:59 nft_synproxy_do_eval+0x335/0x550 net/netfilter/nft_synproxy.c:141 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:6212 [inline] __netif_receive_skb net/core/dev.c:6325 [inline] process_backlog+0xa34/0x1860 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 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:bpf_ksym_find kernel/bpf/core.c:717 [inline] RIP: 0010:is_bpf_text_address+0x26b/0x2b0 kernel/bpf/core.c:749 Code: ff eb 24 e8 e7 ad ef ff c6 05 ea 98 69 0e 01 48 c7 c7 e0 06 f4 8b be 66 03 00 00 48 c7 c2 80 07 f4 8b e8 58 aa cb ff 48 85 db <0f> 95 c0 48 81 fb 20 02 00 00 40 0f 95 c5 40 20 c5 48 c7 c7 60 9c RSP: 0018:ffffc900035f7410 EFLAGS: 00000246 RAX: ffffffff81d75360 RBX: 0000000000000000 RCX: ffff888030889f00 RDX: 0000000000000000 RSI: ffffffff8c4bdb60 RDI: ffffffff8c4bdb20 RBP: 0000000000000001 R08: ffffffff81d75176 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 00000000000017e8 R13: dffffc0000000000 R14: 00007fcff89a3636 R15: 0000000000000000 kernel_text_address+0xa5/0xe0 kernel/extable.c:125 __kernel_text_address+0xd/0x30 kernel/extable.c:79 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:385 arch_stack_walk+0xfb/0x150 arch/x86/kernel/stacktrace.c:26 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:5767 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:4612 [inline] slab_alloc_node mm/slub.c:4945 [inline] kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959 prepare_creds+0x30/0x820 kernel/cred.c:185 copy_creds+0x109/0x9f0 kernel/cred.c:286 copy_process+0xd1f/0x4390 kernel/fork.c:2153 kernel_clone+0x2d7/0x940 kernel/fork.c:2748 __do_sys_clone kernel/fork.c:2889 [inline] __se_sys_clone kernel/fork.c:2873 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2873 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: 0033:0x7fcff89a3636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffd70604c70 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffd70604c78 RCX: 00007fcff89a3636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffd706251c0 R08: 0000000000000000 R09: 0000000000000001 R10: 00007fcff88cfa50 R11: 0000000000000246 R12: 00007ffd70604db0 R13: 0000000000000000 R14: 0000000000000000 R15: 000055d5a490cac0