rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6172/1:b..l rcu: (detected by 1, t=10502 jiffies, g=13081, q=1365 ncpus=2) task:kworker/1:7 state:R running task stack:27336 pid:6172 tgid:6172 ppid:2 task_flags:0x4208060 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7256 irqentry_exit+0x6f/0x90 kernel/entry/common.c:211 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:rcu_read_lock include/linux/rcupdate.h:868 [inline] RIP: 0010:class_rcu_constructor include/linux/rcupdate.h:1195 [inline] RIP: 0010:unwind_next_frame+0xc6/0x2390 arch/x86/kernel/unwind_orc.c:479 Code: 33 00 4c 8d 3d 00 00 00 00 48 c7 c7 e0 d6 f3 8d 31 f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 41 57 e8 ee c4 29 00 48 83 c4 08 65 fc d2 09 85 c0 74 3a e8 9c c2 32 00 84 c0 75 31 e8 53 fc d2 RSP: 0018:ffffc9000b327238 EFLAGS: 00000282 RAX: f0bcec01f22d7700 RBX: ffffffff821a7538 RCX: f0bcec01f22d7700 RDX: 0000000000000000 RSI: ffffffff8d8f50ca RDI: ffffffff8bbf08e0 RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff81738c45 R10: ffffc9000b327358 R11: ffffffff81ac2e10 R12: 1ffff92001664e61 R13: ffffc9000b327340 R14: ffffc9000b327308 R15: ffffffff81738c45 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf5/0x1f0 mm/page_owner.c:156 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:311 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1394 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2901 discard_slab mm/slub.c:3330 [inline] __put_partials+0x146/0x170 mm/slub.c:3876 put_cpu_partial+0x1f2/0x2e0 mm/slub.c:3951 __slab_free+0x2b9/0x390 mm/slub.c:5929 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_kmalloc+0x22/0xb0 mm/kasan/common.c:408 kasan_kmalloc include/linux/kasan.h:262 [inline] __do_kmalloc_node mm/slub.c:5650 [inline] __kmalloc_node_track_caller_noprof+0x568/0x800 mm/slub.c:5759 kvasprintf+0xdc/0x190 lib/kasprintf.c:25 __kthread_create_on_node+0x1c6/0x3e0 kernel/kthread.c:519 kthread_create_on_node+0xdd/0x130 kernel/kthread.c:587 create_worker+0x299/0x720 kernel/workqueue.c:2802 maybe_create_worker kernel/workqueue.c:3063 [inline] manage_workers kernel/workqueue.c:3140 [inline] worker_thread+0x33e/0xda0 kernel/workqueue.c:3402 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 6471 jiffies! g13081 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 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: 5148 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: krxrpcd rxrpc_peer_keepalive_worker RIP: 0010:skb_put+0x128/0x210 net/core/skbuff.c:2584 Code: 85 e5 00 00 00 45 8b 24 24 89 ef 44 89 e6 e8 7f 30 a0 f8 44 39 e5 77 1f e8 b5 2e a0 f8 49 01 df 4c 89 f8 48 83 c4 10 5b 41 5c <41> 5d 41 5e 41 5f 5d e9 7c 8f 29 02 cc e8 96 2e a0 f8 4c 8b 7c 24 RSP: 0018:ffffc90000007138 EFLAGS: 00000286 RAX: ffff88804f38c168 RBX: 0000000000000014 RCX: ffff88803319bc80 RDX: 0000000000000100 RSI: 0000000000000180 RDI: 000000000000017c RBP: 000000000000017c R08: 00000000000080fe R09: 0c00000000000000 R10: 00000000000080fe R11: 0c00000000000000 R12: dffffc0000000000 R13: 0000000000000014 R14: ffff888050275640 R15: ffff88804f38c168 FS: 0000000000000000(0000) GS:ffff88812613b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000b1030 CR3: 0000000077ca2000 CR4: 00000000003526f0 Call Trace: synproxy_send_client_synack_ipv6+0x3f9/0xca0 net/netfilter/nf_synproxy_core.c:882 nft_synproxy_eval_v6+0x36e/0x560 net/netfilter/nft_synproxy.c:90 nft_synproxy_do_eval+0x3d7/0x570 net/netfilter/nft_synproxy.c:145 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x40c/0x1920 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x25d/0x340 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x206/0x3a0 include/linux/netfilter.h:316 ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:500 NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6079 [inline] __netif_receive_skb+0xd3/0x380 net/core/dev.c:6192 process_backlog+0x60e/0x14f0 net/core/dev.c:6544 __napi_poll+0xc7/0x360 net/core/dev.c:7594 napi_poll net/core/dev.c:7657 [inline] net_rx_action+0x5f7/0xdf0 net/core/dev.c:7784 handle_softirqs+0x286/0x870 kernel/softirq.c:622 do_softirq+0xec/0x180 kernel/softirq.c:523 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:396 [inline] rxrpc_peer_keepalive_worker+0x45a/0xde0 net/rxrpc/peer_event.c:337 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245