rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=298321, q=1862 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 9581 (4295091325-4295081744), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 9581 jiffies! g298321 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:27536 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: 3231 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_tt_purge RIP: 0010:rb_add_linked include/linux/rbtree.h:283 [inline] RIP: 0010:timerqueue_linked_add+0x2b6/0x2e0 lib/timerqueue.c:96 Code: 74 08 4c 89 ff e8 ba 86 8b f6 49 83 3f 00 0f 94 c0 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 10 21 07 00 cc e8 da 2d 20 f6 <48> 83 c3 08 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 71 RSP: 0018:ffffc900000068a0 EFLAGS: 00000006 RAX: ffffffff8ba588d6 RBX: ffff8880b8628418 RCX: ffff888032830000 RDX: 0000000000010100 RSI: ffff8880b8628418 RDI: ffff88808ae0d300 RBP: dffffc0000000000 R08: ffff88808ae0d317 R09: 0000000000000000 R10: ffff88808ae0d308 R11: ffffed10115c1a63 R12: 1ffff110170c5078 R13: ffff88808ae0d300 R14: 1ffff110115c1a63 R15: ffff88808ae0d318 FS: 0000000000000000(0000) GS:ffff88812528b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f61020127ec CR3: 00000000a580e000 CR4: 00000000003526f0 Call Trace: enqueue_hrtimer+0x18e/0x2c0 kernel/time/hrtimer.c:1117 __run_hrtimer kernel/time/hrtimer.c:1946 [inline] __hrtimer_run_queues+0x4d2/0xa20 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:198 Code: f7 e8 9d e8 f5 f5 f7 c3 00 02 00 00 74 05 e8 10 83 21 f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 b4 67 e7 f5 65 8b 05 ad ee 8c 07 85 c0 74 18 5b 41 5e e9 51 48 RSP: 0018:ffffc90000006c08 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000286 RCX: 0000000080000302 RDX: 0000000000000002 RSI: ffffffff8dfafc25 RDI: 0000000000000001 RBP: 0000000000000000 R08: ffffffff90309df7 R09: 1ffffffff20613be R10: dffffc0000000000 R11: fffffbfff20613bf R12: ffff88815feee730 R13: ffff88815feee640 R14: ffffffff9a6d3e88 R15: 0000000000000001 __debug_check_no_obj_freed lib/debugobjects.c:1135 [inline] debug_check_no_obj_freed+0x52e/0x550 lib/debugobjects.c:1156 slab_free_hook mm/slub.c:2620 [inline] slab_free mm/slub.c:6251 [inline] kmem_cache_free+0xfd/0x650 mm/slub.c:6378 packet_rcv+0x175/0x1730 net/packet/af_packet.c:2224 dev_queue_xmit_nit+0xa39/0xad0 net/core/dev.c:2606 xmit_one net/core/dev.c:3884 [inline] dev_hard_start_xmit+0x1c1/0x830 net/core/dev.c:3904 __dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4871 dev_queue_xmit include/linux/netdevice.h:3428 [inline] neigh_hh_output include/net/neighbour.h:544 [inline] neigh_output include/net/neighbour.h:558 [inline] ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:236 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:437 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:6203 [inline] __netif_receive_skb net/core/dev.c:6316 [inline] process_backlog+0xaa3/0x1950 net/core/dev.c:6667 __napi_poll+0xae/0x340 net/core/dev.c:7726 napi_poll net/core/dev.c:7789 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7946 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 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_tt_local_purge+0x2a7/0x340 net/batman-adv/translation-table.c:1363 batadv_tt_purge+0x35/0x9e0 net/batman-adv/translation-table.c:3557 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397 rescuer_thread+0x827/0x1130 kernel/workqueue.c:3621 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