sched: DL replenish lagged too much rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P28754/1:b..l rcu: (detected by 0, t=10503 jiffies, g=116701, q=3775 ncpus=2) task:syz.2.5965 state:R running task stack:26712 pid:28754 tgid:28753 ppid:17694 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7552 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:write_comp_data kernel/kcov.c:246 [inline] RIP: 0010:__sanitizer_cov_trace_cmp4+0x17/0x90 kernel/kcov.c:288 Code: 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 15 18 48 74 11 65 8b 0d 39 48 74 11 <81> e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 1c 17 00 00 RSP: 0018:ffffc90003d97ac0 EFLAGS: 00000246 RAX: ffffffff89785691 RBX: 000000000000000e RCX: 0000000080000000 RDX: ffff88802d0b1f00 RSI: 000000000000000e RDI: 000000000000000e RBP: 000000000000000e R08: ffff88802d0b1f00 R09: 0000000000000002 R10: 0000000000000010 R11: 0000000000000002 R12: dffffc0000000000 R13: 1ffff920007b2f84 R14: ffffc90003d97c22 R15: 000000000000000e bpf_flow_dissect+0x3d1/0x730 net/core/flow_dissector.c:1027 bpf_prog_test_run_flow_dissector+0x3a4/0x610 net/bpf/test_run.c:1524 bpf_prog_test_run+0x2c5/0x340 kernel/bpf/syscall.c:4742 __sys_bpf+0x643/0x950 kernel/bpf/syscall.c:6292 __do_sys_bpf kernel/bpf/syscall.c:6387 [inline] __se_sys_bpf kernel/bpf/syscall.c:6385 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6385 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: 0033:0x7f6ac9b9ce59 RSP: 002b:00007f6acaa33028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f6ac9e15fa0 RCX: 00007f6ac9b9ce59 RDX: 0000000000000050 RSI: 00002000000002c0 RDI: 000000000000000a RBP: 00007f6ac9c32e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6ac9e16038 R14: 00007f6ac9e15fa0 R15: 00007ffc9f34be38 rcu: rcu_preempt kthread starved for 3623 jiffies! g116701 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:28040 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: CPU: 0 UID: 0 PID: 9165 Comm: kworker/u8:53 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:__sanitizer_cov_trace_pc+0x5c/0x70 kernel/kcov.c:235 Code: f8 16 00 00 83 fa 02 75 21 48 8b 91 00 17 00 00 48 8b 32 48 8d 7e 01 8b 89 fc 16 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 08 cc cc cc cc cc 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 RSP: 0018:ffffc90000007090 EFLAGS: 00000246 RAX: ffffffff8a553f99 RBX: ffff88807d7eba00 RCX: ffff88807c5f9f00 RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000100 R12: dffffc0000000000 R13: ffff88807d7eba20 R14: ffffffff8a553ead R15: ffff888029630000 FS: 0000000000000000(0000) GS:ffff88812527c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055556e7d44e8 CR3: 000000000e746000 CR4: 00000000003526f0 Call Trace: dst_dev_rcu include/net/dst.h:582 [inline] ip6_dst_mtu_maybe_forward include/net/ip6_route.h:379 [inline] ip6_mtu+0x169/0x490 net/ipv6/route.c:3290 __ip6_finish_output net/ipv6/ip6_output.c:200 [inline] ip6_finish_output+0x134/0x480 net/ipv6/ip6_output.c:219 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x337/0x540 net/ipv6/ip6_output.c:246 synproxy_send_tcp_ipv6+0x549/0x700 net/netfilter/nf_synproxy_core.c:861 synproxy_send_client_synack_ipv6+0x83f/0xcd0 net/netfilter/nf_synproxy_core.c:907 nft_synproxy_eval_v6+0x37b/0x530 net/netfilter/nft_synproxy.c:91 nft_synproxy_do_eval+0x3d1/0x550 net/netfilter/nft_synproxy.c:146 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 ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:545 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+0x774/0x1860 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+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_global_purge net/batman-adv/translation-table.c:2298 [inline] batadv_tt_purge+0x4ae/0xa10 net/batman-adv/translation-table.c:3558 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478 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