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): P14068/1:b..l rcu: (detected by 0, t=10503 jiffies, g=80413, q=782 ncpus=2) task:syz.8.1979 state:R running task stack:25576 pid:14068 tgid:14068 ppid:12344 task_flags:0x40044c flags:0x10080003 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] zap_pte_range mm/memory.c:1884 [inline] zap_pmd_range mm/memory.c:1946 [inline] zap_pud_range mm/memory.c:1975 [inline] zap_p4d_range mm/memory.c:1996 [inline] unmap_page_range+0x3a7f/0x4370 mm/memory.c:2017 unmap_single_vma mm/memory.c:2060 [inline] unmap_vmas+0x399/0x580 mm/memory.c:2104 exit_mmap+0x240/0xb40 mm/mmap.c:1280 __mmput+0x118/0x430 kernel/fork.c:1133 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:954 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_int80_emulation+0x2a0/0x390 arch/x86/entry/syscall_32.c:175 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:621 RIP: 0023:0xf72585d0 RSP: 002b:00000000f75af894 EFLAGS: 00000286 ORIG_RAX: 00000000000001b3 RAX: 00000000000000f4 RBX: 00000000f75af900 RCX: 0000000000000058 RDX: 00000000f71e5dc0 RSI: 00000000f54adb40 RDI: 00000000ffffffd4 RBP: 000000000000000b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 4125 jiffies! g80413 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7256 irqentry_exit+0x6f/0x90 kernel/entry/common.c:211 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_release+0x2c5/0x3e0 kernel/locking/lockdep.c:5893 Code: 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b 05 ab fa f3 10 48 3b 44 24 28 0f 85 8b 00 00 00 48 83 c4 30 5b <41> 5c 41 5d 41 5e 41 5f 5d e9 0d ff b2 09 cc 90 0f 0b 90 e9 5d fd RSP: 0018:ffffc900001572a8 EFLAGS: 00000286 RAX: 61571871ec518200 RBX: ffffffff90310101 RCX: 61571871ec518200 RDX: 0000000000000001 RSI: ffffffff8d9d457d RDI: ffffffff8bc07360 RBP: ffff88801c2d6618 R08: ffffc90000157950 R09: 0000000000000000 R10: ffffc900001573f8 R11: fffff5200002ae81 R12: 0000000000000001 R13: 0000000000000001 R14: ffffffff8e13d2e0 R15: ffff88801c2d5ac0 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:897 [inline] class_rcu_destructor include/linux/rcupdate.h:1195 [inline] unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 unpoison_slab_object mm/kasan/common.c:342 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:368 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4962 [inline] slab_alloc_node mm/slub.c:5272 [inline] kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5279 kmem_alloc_batch lib/debugobjects.c:371 [inline] fill_pool+0x100/0x570 lib/debugobjects.c:403 debug_objects_fill_pool lib/debugobjects.c:725 [inline] debug_object_assert_init+0x2b1/0x380 lib/debugobjects.c:1003 debug_timer_assert_init kernel/time/timer.c:803 [inline] debug_assert_init kernel/time/timer.c:848 [inline] __try_to_del_timer_sync+0x29/0x3a0 kernel/time/timer.c:1457 __timer_delete_sync+0x1fe/0x2d0 kernel/time/timer.c:1620 schedule_timeout+0x133/0x270 kernel/time/sleep_timeout.c:100 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 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: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x6c/0xb0 kernel/rcu/tree.c:751 Code: 7f 00 48 c7 c3 d8 cf 92 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d 19 12 eb 10 74 11 83 e0 04 e8 02 5b 41 5e 41 5f c3 cc cc cc cc cc e8 31 ea 8c ff eb e8 48 RSP: 0018:ffffc90000006b78 EFLAGS: 00000202 RAX: 0000000000000004 RBX: ffff8880b8632fd8 RCX: d0a07026576a1c00 RDX: 0000000000000000 RSI: ffffffff8bc07340 RDI: ffffffff8bc07300 RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff8173cd25 R10: ffffc90000006cb8 R11: ffffffff81ac6cb0 R12: 1ffff92000000d8d R13: ffffc90000006ca0 R14: ffffffff8da0ddd0 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888125d06000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000f50794d6 CR3: 000000007dd62000 CR4: 00000000003526f0 Call Trace: rcu_read_lock include/linux/rcupdate.h:868 [inline] class_rcu_constructor include/linux/rcupdate.h:1195 [inline] unwind_next_frame+0xd4/0x2390 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 unpoison_slab_object mm/kasan/common.c:342 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:368 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4962 [inline] slab_alloc_node mm/slub.c:5272 [inline] kmem_cache_alloc_node_noprof+0x433/0x710 mm/slub.c:5324 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:660 alloc_skb include/linux/skbuff.h:1383 [inline] synproxy_send_client_synack_ipv6+0x169/0xca0 net/netfilter/nf_synproxy_core.c:873 nft_synproxy_eval_v6+0x36e/0x560 net/netfilter/nft_synproxy.c:90 nft_synproxy_do_eval+0x3d7/0x570 net/netfilter/nft_synproxy.c:145 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x40c/0x1920 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x25d/0x340 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x206/0x3a0 include/linux/netfilter.h:316 ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:500 NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6079 [inline] __netif_receive_skb+0xd3/0x380 net/core/dev.c:6192 process_backlog+0x60e/0x14f0 net/core/dev.c:6544 __napi_poll+0xc7/0x360 net/core/dev.c:7594 napi_poll net/core/dev.c:7657 [inline] net_rx_action+0x5f7/0xdf0 net/core/dev.c:7784 handle_softirqs+0x286/0x870 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: cc cc cc cc cc cc cc 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 33 71 1a 00 f3 0f 1e fa fb f4 c8 e6 02 00 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffffff8de07d80 EFLAGS: 000002c6 RAX: d0a07026576a1c00 RBX: ffffffff8196bb87 RCX: d0a07026576a1c00 RDX: 0000000000000001 RSI: ffffffff8d7eb243 RDI: ffffffff8bc07360 RBP: ffffffff8de07ea8 R08: ffff8880b8632fdb R09: 1ffff110170c65fb R10: dffffc0000000000 R11: ffffed10170c65fc R12: ffffffff8f9e1570 R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1bd2a40 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x1e7/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428 rest_init+0x2de/0x300 init/main.c:757 start_kernel+0x3ae/0x410 init/main.c:1111 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147