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): P6863/1:b..l rcu: (detected by 0, t=10502 jiffies, g=10461, q=1678799 ncpus=2) task:syz.3.249 state:R running task stack:25920 pid:6863 tgid:6862 ppid:5815 task_flags:0x40044c flags:0x00004006 Call Trace: <TASK> context_switch kernel/sched/core.c:5378 [inline] __schedule+0xf43/0x5890 kernel/sched/core.c:6765 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6944 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] zap_pte_range mm/memory.c:1772 [inline] zap_pmd_range mm/memory.c:1834 [inline] zap_pud_range mm/memory.c:1863 [inline] zap_p4d_range mm/memory.c:1884 [inline] unmap_page_range+0xee3/0x4390 mm/memory.c:1905 unmap_single_vma+0x194/0x2b0 mm/memory.c:1951 unmap_vmas+0x22f/0x490 mm/memory.c:1995 exit_mmap+0x1c1/0xba0 mm/mmap.c:1284 __mmput+0x12a/0x410 kernel/fork.c:1356 mmput+0x62/0x70 kernel/fork.c:1378 exit_mm kernel/exit.c:570 [inline] do_exit+0x9ba/0x2d70 kernel/exit.c:925 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087 get_signal+0x24ed/0x26c0 kernel/signal.c:3036 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff10138d169 RSP: 002b:00007ff1021b4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: 0000400000000000 RBX: 00007ff1015a5fa0 RCX: 00007ff10138d169 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000400000000000 RBP: 00007ff10140e2a0 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff1015a5fa0 R15: 00007fff5ca9db48 </TASK> rcu: rcu_preempt kthread starved for 4105 jiffies! g10461 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:27552 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:5378 [inline] __schedule+0xf43/0x5890 kernel/sched/core.c:6765 __schedule_loop kernel/sched/core.c:6842 [inline] schedule+0xe7/0x350 kernel/sched/core.c:6857 schedule_timeout+0x124/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2024 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2226 kthread+0x3af/0x750 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> 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: 30 Comm: khungtaskd Not tainted 6.14.0-rc4-syzkaller-00169-g1e15510b71c9 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:unwind_done arch/x86/include/asm/unwind.h:50 [inline] RIP: 0010:unwind_get_return_address+0x12/0xa0 arch/x86/kernel/unwind_orc.c:366 Code: 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 48 89 fa 55 <48> c1 ea 03 53 48 89 fb 0f b6 04 02 84 c0 74 04 3c 03 7e 59 8b 03 RSP: 0018:ffffc90000a17888 EFLAGS: 00000202 RAX: dffffc0000000000 RBX: ffffc90000a17898 RCX: 0000000000000000 RDX: ffffc90000a17898 RSI: ffffc90000a17e38 RDI: ffffc90000a17898 RBP: ffffc90000a17928 R08: ffffc90000a178cc R09: ffffffff91518d0e R10: ffffc90000a17898 R11: 0000000000056271 R12: ffffffff81a59b50 R13: ffffc90000a17958 R14: 0000000000000000 R15: ffff88801da8c880 FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000040000002f000 CR3: 000000003379e000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <NMI> </NMI> <IRQ> arch_stack_walk+0xa7/0x100 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x95/0xd0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2353 [inline] slab_free mm/slub.c:4609 [inline] kmem_cache_free+0x2e2/0x4d0 mm/slub.c:4711 kfree_skbmem+0x1a4/0x1f0 net/core/skbuff.c:1058 __kfree_skb net/core/skbuff.c:1115 [inline] sk_skb_reason_drop+0x136/0x1a0 net/core/skbuff.c:1152 kfree_skb_reason include/linux/skbuff.h:1271 [inline] enqueue_to_backlog+0x47f/0xe60 net/core/dev.c:5121 netif_rx_internal+0x108/0x5f0 net/core/dev.c:5416 __netif_rx+0x88/0xb0 net/core/dev.c:5436 loopback_xmit+0x284/0x700 drivers/net/loopback.c:89 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3800 [inline] dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3816 sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0x53f/0x1a10 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:4108 [inline] __dev_queue_xmit+0x2aa4/0x43e0 net/core/dev.c:4615 dev_queue_xmit include/linux/netdevice.h:3313 [inline] neigh_hh_output include/net/neighbour.h:523 [inline] neigh_output include/net/neighbour.h:537 [inline] ip_finish_output2+0xc34/0x2180 net/ipv4/ip_output.c:236 __ip_finish_output net/ipv4/ip_output.c:314 [inline] __ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:296 ip_finish_output+0x35/0x380 net/ipv4/ip_output.c:324 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:434 dst_output include/net/dst.h:459 [inline] ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:130 synproxy_send_tcp.isra.0+0x439/0x630 net/netfilter/nf_synproxy_core.c:439 synproxy_send_client_synack+0x6f7/0x900 net/netfilter/nf_synproxy_core.c:484 nft_synproxy_eval_v4 net/netfilter/nft_synproxy.c:59 [inline] nft_synproxy_do_eval+0xa49/0xd60 net/netfilter/nft_synproxy.c:141 expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline] nft_do_chain+0x2e6/0x18f0 net/netfilter/nf_tables_core.c:288 nft_do_chain_inet+0x18b/0x350 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:626 nf_hook.constprop.0+0x42e/0x750 include/linux/netfilter.h:269 NF_HOOK include/linux/netfilter.h:312 [inline] ip_local_deliver+0x169/0x1f0 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:469 [inline] ip_rcv_finish net/ipv4/ip_input.c:447 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] ip_rcv+0x2c3/0x5d0 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core+0x199/0x1e0 net/core/dev.c:5893 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6006 process_backlog+0x443/0x15f0 net/core/dev.c:6354 __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:7188 napi_poll net/core/dev.c:7257 [inline] net_rx_action+0xa94/0x1010 net/core/dev.c:7379 handle_softirqs+0x213/0x8f0 kernel/softirq.c:561 __do_softirq kernel/softirq.c:595 [inline] invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:662 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1049 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] RIP: 0010:watchdog+0x2b5/0x12b0 kernel/hung_task.c:399 Code: 8d 87 18 04 00 00 48 b9 00 00 00 00 00 fc ff df 48 89 44 24 10 48 c1 e8 03 80 3c 08 00 0f 85 7f 0f 00 00 49 8b 9f 18 04 00 00 <48> b9 00 00 00 00 00 fc ff df 48 8d 6b 10 48 89 e8 48 c1 e8 03 80 RSP: 0018:ffffc90000a67db0 EFLAGS: 00000246 RAX: 1ffff11005931a34 RBX: ffff88802c981440 RCX: dffffc0000000000 RDX: ffff88801da8c880 RSI: ffffffff81b9faaa RDI: ffff88802c98a948 RBP: 00000000003fff62 R08: 0000000000000005 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88802c980d90 R13: 00000000003fff63 R14: 00000000fffffabe R15: ffff88802c98cd88 kthread+0x3af/0x750 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK>