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): P8551/1:b..l.. rcu: (detected by 0, t=10502 jiffies, g=58197, q=907146 ncpus=1) task:syz.2.854 state:R running task stack:26120 pid:8551 tgid:8550 ppid:5636 task_flags:0x40054c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5583 [inline] __schedule+0x17dd/0x5830 kernel/sched/core.c:7382 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7662 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:543 [inline] irqentry_exit+0x14f/0x9b0 kernel/entry/common.c:154 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:__page_table_check_zero+0x14a/0x430 mm/page_table_check.c:139 Code: 74 0c 48 c7 c7 10 bf ab 8e e8 92 0a f4 ff 4c 2b 35 8b 67 5f 0c 49 c1 fe 06 4c 89 74 24 08 bf 20 00 00 00 89 ee e8 76 f7 7c ff <83> fd 1f 0f 87 a0 02 00 00 e8 58 f2 7c ff bb 01 00 00 00 89 e9 d3 RSP: 0018:ffffc900035bf748 EFLAGS: 00000293 RAX: ffffffff824c579a RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff888020bf9f40 RSI: 0000000000000000 RDI: 0000000000000020 RBP: 0000000000000000 R08: ffffffff824c56bc R09: 0000000000000000 R10: dffffc0000000000 R11: ffffed100f5cc5a6 R12: ffffea0001efdd00 R13: 00000e000014a123 R14: 000000000007bf74 R15: ffffffff824c56bc page_table_check_free include/linux/page_table_check.h:46 [inline] __free_pages_prepare mm/page_alloc.c:1404 [inline] __free_frozen_pages+0xca7/0xd90 mm/page_alloc.c:2957 __slab_free+0x269/0x2c0 mm/slub.c:5926 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:361 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4720 [inline] slab_alloc_node mm/slub.c:5033 [inline] kmem_cache_alloc_noprof+0x2b4/0x600 mm/slub.c:5047 taskstats_tgid_alloc kernel/taskstats.c:539 [inline] taskstats_exit+0x19e/0xe10 kernel/taskstats.c:578 do_exit+0x688/0x2360 kernel/exit.c:949 do_group_exit+0x22d/0x2f0 kernel/exit.c:1123 get_signal+0x1216/0x12c0 kernel/signal.c:3112 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f429519f559 RSP: 002b:00007f4296082028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: fffffffffffffe00 RBX: 00007f4295425fa0 RCX: 00007f429519f559 RDX: 000000000000001c RSI: 00002000000006c0 RDI: 0000000000000009 RBP: 00007f4295236b20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4295426038 R14: 00007f4295425fa0 R15: 00007fffb0d432f8 rcu: rcu_preempt kthread starved for 764 jiffies! g58197 f0x2 RCU_GP_WAIT_FQS(5) ->state=R ->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:28104 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5583 [inline] __schedule+0x17dd/0x5830 kernel/sched/core.c:7382 __schedule_loop kernel/sched/core.c:7459 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7474 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x1230 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9c/0x340 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 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: 3231 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Workqueue: bat_events batadv_dat_purge RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x80 kernel/kcov.c:216 Code: 89 fb e8 23 00 00 00 48 8b 3d 64 06 e3 0c 48 89 de 5b e9 c3 4b 6b 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 04 24 65 48 8b 0d f8 55 21 13 65 48 8b 15 f8 55 RSP: 0018:ffffc900000079f8 EFLAGS: 00000246 RAX: ffffffff89e5e151 RBX: ffff88815dd6c000 RCX: 8000000000000100 RDX: ffff888033083e80 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000007c40 R08: 0000000000000100 R09: 0000000000000002 R10: 000000000000a888 R11: 8000000000000100 R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88815dd6c098 FS: 0000000000000000(0000) GS:ffff888123376000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055be9e204a88 CR3: 0000000026eea000 CR4: 00000000003526f0 Call Trace: __netif_receive_skb_core+0x25fe/0x30c0 net/core/dev.c:6317 __netif_receive_skb_one_core net/core/dev.c:6412 [inline] __netif_receive_skb net/core/dev.c:6527 [inline] process_backlog+0x727/0x18b0 net/core/dev.c:6878 __napi_poll+0xaa/0x330 net/core/dev.c:7947 napi_poll net/core/dev.c:8010 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:8167 handle_softirqs+0x265/0x8d0 kernel/softirq.c:669 do_softirq+0x77/0xd0 kernel/softirq.c:569 __local_bh_enable_ip+0x100/0x140 kernel/softirq.c:473 spin_unlock_bh include/linux/spinlock.h:407 [inline] __batadv_dat_purge net/batman-adv/distributed-arp-table.c:252 [inline] batadv_dat_purge+0x2d7/0x3c0 net/batman-adv/distributed-arp-table.c:271 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 rescuer_thread+0x84a/0x12a0 kernel/workqueue.c:3803 kthread+0x38b/0x480 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