rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=14689, q=624120 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 6738 (4294974745-4294968007), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 6739 jiffies! g14689 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:27784 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5397 [inline] __schedule+0x116a/0x5de0 kernel/sched/core.c:6786 __schedule_loop kernel/sched/core.c:6864 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6879 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2256 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:__update_cpu_freelist_fast mm/slub.c:3606 [inline] RIP: 0010:__slab_alloc_node mm/slub.c:4042 [inline] RIP: 0010:slab_alloc_node mm/slub.c:4185 [inline] RIP: 0010:kmem_cache_alloc_node_noprof+0x160/0x3b0 mm/slub.c:4249 Code: 74 a5 48 85 db 75 87 eb 9e 48 85 ff 74 99 48 85 db 74 94 41 ba ff ff ff ff 41 8b 44 24 28 49 8b 34 24 48 8d 4a 08 48 8b 1c 07 <48> 89 f8 65 48 0f c7 0e 0f 85 29 ff ff ff 41 8b 44 24 28 0f 0d 0c RSP: 0018:ffffc900000073f0 EFLAGS: 00000246 RAX: 0000000000000078 RBX: ffff88818f12edc0 RCX: 0000000000c01910 RDX: 0000000000c01908 RSI: ffffffff93d2f970 RDI: ffff88818f12ec80 RBP: ffffc90000007448 R08: 0000000000000005 R09: 0000000000000000 R10: 00000000ffffffff R11: 0000000000000001 R12: ffff88801f6f9a00 R13: 0000000000000820 R14: 00000000ffffffff R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124713000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000023000 CR3: 000000004b0cd000 CR4: 00000000003526f0 Call Trace: __alloc_skb+0x2b2/0x380 net/core/skbuff.c:660 alloc_skb include/linux/skbuff.h:1336 [inline] synproxy_send_client_synack_ipv6+0x1af/0x7e0 net/netfilter/nf_synproxy_core.c:873 nft_synproxy_eval_v6 net/netfilter/nft_synproxy.c:90 [inline] nft_synproxy_do_eval+0x93b/0xd80 net/netfilter/nft_synproxy.c:145 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x2e6/0x1920 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x18a/0x340 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623 nf_hook.constprop.0+0x422/0x750 include/linux/netfilter.h:272 NF_HOOK include/linux/netfilter.h:315 [inline] ip6_input+0xe0/0x2f0 net/ipv6/ip6_input.c:491 dst_input include/net/dst.h:469 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ipv6_rcv+0x265/0x680 net/ipv6/ip6_input.c:309 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5977 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6090 process_backlog+0x442/0x15e0 net/core/dev.c:6442 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7414 napi_poll net/core/dev.c:7478 [inline] net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605 handle_softirqs+0x219/0x8e0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: cb 6b 02 e9 83 fb 02 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 43 b9 21 00 fb f4 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c6 RAX: 0000000001203d8b RBX: 0000000000000000 RCX: ffffffff8b885c99 RDX: 0000000000000000 RSI: ffffffff8de32e47 RDI: ffffffff8c158f60 RBP: fffffbfff1c52ef0 R08: 0000000000000001 R09: ffffed1017086645 R10: ffff8880b843322b R11: 0000000000000001 R12: 0000000000000000 R13: ffffffff8e297780 R14: ffffffff90a98750 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:749 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423 rest_init+0x16b/0x2b0 init/main.c:745 start_kernel+0x3ee/0x4d0 init/main.c:1102 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x148