rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=147421, q=1415 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10495 (4295038267-4295027772), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10496 jiffies! g147421 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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:27176 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0x164/0x360 kernel/sched/core.c:7322 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 3228 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:101 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline] RIP: 0010:unwind_next_frame+0x4c3/0x2550 arch/x86/kernel/unwind_orc.c:510 Code: 01 4c 8b 6c 24 50 49 bc 00 00 00 00 00 fc ff df 4c 8b 7c 24 10 49 8d 6e 38 0f 84 8a 16 00 00 e9 ee 01 00 00 49 89 d5 49 89 d7 <4c> 89 e0 4c 29 f8 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 48 83 RSP: 0018:ffffc90000a07f40 EFLAGS: 00000246 RAX: ffffffff90535790 RBX: ffffffff90535794 RCX: ffffffff90535798 RDX: ffffffff90535794 RSI: ffffffff90d3abf0 RDI: ffffffff8c2910c0 RBP: ffffffff8231171b R08: 0000000000000019 R09: 0000000000000000 R10: ffffc90000a08038 R11: ffffffff81b10630 R12: ffffffff90535798 R13: ffffffff90535794 R14: ffffc90000a07fe8 R15: ffffffff90535798 FS: 0000000000000000(0000) GS:ffff88812537c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3d3fc866f3 CR3: 000000000e746000 CR4: 00000000003526f0 Call Trace: arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2700 [inline] slab_free mm/slub.c:6310 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6437 nft_synproxy_eval_v4+0x383/0x530 net/netfilter/nft_synproxy.c:61 nft_synproxy_do_eval+0x335/0x550 net/netfilter/nft_synproxy.c:142 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:6206 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0xa34/0x1860 net/core/dev.c:6670 __napi_poll+0xaa/0x330 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7949 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:rcu_preempt_read_exit kernel/rcu/tree_plugin.h:396 [inline] RIP: 0010:__rcu_read_unlock+0x32/0xe0 kernel/rcu/tree_plugin.h:435 Code: 41 55 41 54 53 49 bf 00 00 00 00 00 fc ff df 65 48 8b 3d a9 a0 8e 11 48 8d 9f c4 04 00 00 49 89 dc 49 c1 ec 03 43 0f b6 04 3c <84> c0 75 4f ff 0b 75 1d 4c 8d b7 c8 04 00 00 4c 89 f0 48 c1 e8 03 RSP: 0018:ffffc9000dfc78b0 EFLAGS: 00000a03 RAX: 0000000000000000 RBX: ffff8880324684c4 RCX: 0000000080000001 RDX: 0000000000000000 RSI: ffffffff8c291100 RDI: ffff888032468000 RBP: ffffc9000dfc7a28 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffed100367fa1a R12: 1ffff1100648d098 R13: dffffc0000000000 R14: 0000000000000000 R15: dffffc0000000000 rcu_read_unlock include/linux/rcupdate.h:873 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:792 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:853 [inline] batadv_iv_ogm_schedule+0x744/0xff0 net/batman-adv/bat_iv_ogm.c:909 batadv_iv_send_outstanding_bat_ogm_packet+0x625/0x740 net/batman-adv/bat_iv_ogm.c:1798 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397 rescuer_thread+0x7b6/0x10b0 kernel/workqueue.c:3621 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