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): P6740/1:b..l rcu: (detected by 1, t=10503 jiffies, g=18433, q=1527 ncpus=2) task:syz.2.211 state:R running task stack:24000 pid:6740 tgid:6734 ppid:5848 task_flags:0x400140 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b88/0x5240 kernel/sched/core.c:6767 preempt_schedule_irq+0xfe/0x1c0 kernel/sched/core.c:7090 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0xb/0x2f0 kernel/locking/lockdep.c:5826 Code: 95 c0 c3 cc cc cc cc 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 <41> 54 53 48 83 ec 40 4c 89 4c 24 08 45 89 c4 41 89 cd 41 89 d7 89 RSP: 0018:ffffc90003bde738 EFLAGS: 00000246 RAX: 0000000000000001 RBX: 1ffff9200077bd08 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8ed3dfe0 RBP: ffffc90003bde878 R08: 0000000000000000 R09: 0000000000000000 R10: ffffc90003bde890 R11: ffffffff81aee9b0 R12: ffffc90003bde840 R13: dffffc0000000000 R14: ffffffff82229af4 R15: ffffffff816dfbc8 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xd5/0x23b0 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11e/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x11a/0x1d0 kernel/stacktrace.c:122 save_stack+0xfc/0x1f0 mm/page_owner.c:156 __reset_page_owner+0x76/0x1e0 mm/page_owner.c:308 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1262 [inline] __free_frozen_pages+0xde8/0x10a0 mm/page_alloc.c:2680 discard_slab mm/slub.c:2720 [inline] __put_partials+0x160/0x1c0 mm/slub.c:3189 put_cpu_partial+0x17e/0x250 mm/slub.c:3264 __slab_free+0x294/0x390 mm/slub.c:4516 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4151 [inline] slab_alloc_node mm/slub.c:4200 [inline] kmem_cache_alloc_node_noprof+0x1f2/0x3b0 mm/slub.c:4252 __alloc_skb+0x1c2/0x480 net/core/skbuff.c:658 alloc_skb include/linux/skbuff.h:1340 [inline] alloc_skb_with_frags+0xc3/0x830 net/core/skbuff.c:6639 sock_alloc_send_pskb+0x91c/0xa70 net/core/sock.c:2949 sock_alloc_send_skb include/net/sock.h:1796 [inline] __ip_append_data+0x3097/0x4750 net/ipv4/ip_output.c:1119 ip_make_skb+0x19a/0x420 net/ipv4/ip_output.c:1567 udp_sendmsg+0x1c7e/0x2ca0 net/ipv4/udp.c:1478 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x1a6/0x270 net/socket.c:727 ____sys_sendmsg+0x523/0x860 net/socket.c:2566 ___sys_sendmsg net/socket.c:2620 [inline] __sys_sendmmsg+0x3a0/0x7b0 net/socket.c:2709 __do_sys_sendmmsg net/socket.c:2736 [inline] __se_sys_sendmmsg net/socket.c:2733 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2733 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f847b98d169 RSP: 002b:00007f847c721038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f847bba6160 RCX: 00007f847b98d169 RDX: 000000000800001d RSI: 0000200000007fc0 RDI: 0000000000000009 RBP: 00007f847ba0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f847bba6160 R15: 00007f847bccfa28 rcu: rcu_preempt kthread starved for 9622 jiffies! g18433 f0x0 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:26688 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b88/0x5240 kernel/sched/core.c:6767 preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6947 preempt_schedule+0xe4/0xf0 kernel/sched/core.c:6971 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0x134/0x140 kernel/locking/spinlock.c:194 __mod_timer+0xc45/0x10f0 kernel/time/timer.c:1181 schedule_timeout+0x156/0x2b0 kernel/time/sleep_timeout.c:98 rcu_gp_fqs_loop+0x2e1/0x1340 kernel/rcu/tree.c:2046 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2248 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.14.0-syzkaller-12966-ga2cc6ff5ec8f #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:jhash2 include/linux/jhash.h:127 [inline] RIP: 0010:hash_stack lib/stackdepot.c:514 [inline] RIP: 0010:stack_depot_save_flags+0x80/0x940 lib/stackdepot.c:615 Code: 66 15 00 0f 85 0c 04 00 00 43 8d 34 09 46 8d 24 cd 7b 71 f5 75 83 fe 04 72 70 44 89 e3 44 89 e0 4c 89 fa 44 8b 44 24 08 03 02 <03> 5a 04 44 03 62 08 44 89 e7 c1 c7 04 44 29 e0 31 c7 41 01 dc 29 RSP: 0018:ffffc90000a07b90 EFLAGS: 00000282 RAX: 00000000d0b0a6e5 RBX: 0000000019a2b194 RCX: 00000000a3d9f0b5 RDX: ffffc90000a07c18 RSI: 0000000000000024 RDI: 00000000fd389de8 RBP: 00000000c73bbfe3 R08: 0000000000000001 R09: 0000000000000015 R10: 0000000000000000 R11: 0000000000000000 R12: 000000008e8a01a8 R13: ffff88816547cb01 R14: 0000000000000820 R15: ffffc90000a07c00 FS: 0000000000000000(0000) GS:ffff888125099000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe85fc575f7 CR3: 0000000033a80000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kasan_save_stack mm/kasan/common.c:48 [inline] kasan_save_track+0x51/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4151 [inline] slab_alloc_node mm/slub.c:4200 [inline] kmem_cache_alloc_node_noprof+0x1f2/0x3b0 mm/slub.c:4252 __alloc_skb+0x1c2/0x480 net/core/skbuff.c:658 alloc_skb include/linux/skbuff.h:1340 [inline] synproxy_send_client_synack+0x1ae/0xf70 net/netfilter/nf_synproxy_core.c:460 nft_synproxy_eval_v4+0x3cc/0x610 net/netfilter/nft_synproxy.c:59 nft_synproxy_do_eval+0x36a/0xa90 net/netfilter/nft_synproxy.c:141 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x4b2/0x1db0 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x41f/0x6b0 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xc8/0x220 net/netfilter/core.c:626 nf_hook include/linux/netfilter.h:269 [inline] NF_HOOK+0x29b/0x450 include/linux/netfilter.h:312 NF_HOOK+0x3a0/0x450 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5891 [inline] __netif_receive_skb+0x2c9/0x670 net/core/dev.c:6004 process_backlog+0x664/0x15c0 net/core/dev.c:6356 __napi_poll+0xcb/0x480 net/core/dev.c:7328 napi_poll net/core/dev.c:7392 [inline] net_rx_action+0x89d/0x1240 net/core/dev.c:7514 handle_softirqs+0x2d6/0x9b0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xfb/0x220 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:81 Code: cc cc cc cc 0f 1f 00 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 01 18 00 f3 0f 1e fa fb f4 cc cc cc cc 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000197dc0 EFLAGS: 000002c2 RAX: a804af099bad2d00 RBX: ffffffff8197afbe RCX: ffffffff8c30393c RDX: 0000000000000001 RSI: ffffffff8e69b738 RDI: ffffffff8ca1b140 RBP: ffffc90000197f20 R08: ffff8880b8732b5b R09: 1ffff110170e656b R10: dffffc0000000000 R11: ffffed10170e656c R12: 1ffff92000032fd2 R13: 1ffff11003adfb40 R14: 0000000000000001 R15: dffffc0000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:748 default_idle_call+0x74/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x22e/0x5d0 kernel/sched/idle.c:325 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:423 start_secondary+0xfe/0x100 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x147