syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P1205/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=50893, q=1370 ncpus=2)
task:kworker/1:2     state:R  running task     stack:23336 pid:1205  tgid:1205  ppid:2      task_flags:0x4288060 flags:0x00004000
Workqueue: events pcpu_balance_workfn
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x116a/0x5de0 kernel/sched/core.c:6786
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7109
 irqentry_exit+0x36/0x90 kernel/entry/common.c:307
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:unwind_next_frame+0xc53/0x20a0 arch/x86/kernel/unwind_orc.c:641
Code: 00 00 00 fc ff df 48 c1 e8 03 0f b6 34 10 49 8d 40 01 48 89 c7 48 c1 ef 03 0f b6 14 17 4c 89 c7 83 e7 07 40 38 fe 40 0f 9e c7 <40> 84 f6 40 0f 95 c6 40 84 f7 0f 85 e3 10 00 00 83 e0 07 38 c2 40
RSP: 0018:ffffc900041ef720 EFLAGS: 00000297
RAX: ffffffff914b6daf RBX: 0000000000000001 RCX: ffffffff914b6daa
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc900041ef7d8 R08: ffffffff914b6dae R09: 0000000000000000
R10: 0000000000000000 R11: 00000000000110b0 R12: ffffc900041ef7e0
R13: ffffc900041ef790 R14: ffffc900041efb28 R15: ffffc900041ef7c4
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x160/0x1f0 mm/page_owner.c:156
 __reset_page_owner+0x84/0x1a0 mm/page_owner.c:308
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
 vfree+0x1fd/0xb50 mm/vmalloc.c:3434
 pcpu_mem_free mm/percpu.c:523 [inline]
 pcpu_free_chunk mm/percpu.c:1489 [inline]
 pcpu_free_chunk mm/percpu.c:1484 [inline]
 pcpu_destroy_chunk mm/percpu-vm.c:368 [inline]
 pcpu_balance_free+0x5fb/0xaf0 mm/percpu.c:1977
 pcpu_balance_workfn+0x9c2/0xe00 mm/percpu.c:2206
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 7648 jiffies! g50893 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:27784 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x116a/0x5de0 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6879
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2256
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.16.0-rc6-syzkaller-00253-g4871b7cb27f4 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:114 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:128 [inline]
RIP: 0010:__local_bh_disable_ip+0x1c/0xd0 kernel/softirq.c:334
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 53 89 f3 65 8b 05 a1 0e 53 12 a9 00 00 0f 00 0f 85 9d 00 00 00 9c 5d <fa> 65 01 1d 8c 0e 53 12 65 8b 05 85 0e 53 12 31 d8 f6 c4 ff 74 27
RSP: 0018:ffffc900000070e8 EFLAGS: 00000246
RAX: 0000000080000101 RBX: 0000000000000200 RCX: ffffffff8a35fd89
RDX: ffffffff8e297780 RSI: 0000000000000200 RDI: ffffffff8a35fda3
RBP: 0000000000000246 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 1ffff92000000e24 R14: 0000000000000080 R15: ffffc90000007180
FS:  0000000000000000(0000) GS:ffff888124722000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055556908d5c8 CR3: 00000000310fd000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 local_bh_disable include/linux/bottom_half.h:20 [inline]
 ip6_pol_route+0x358/0x1230 net/ipv6/route.c:2300
 pol_lookup_func include/net/ip6_fib.h:617 [inline]
 fib6_rule_lookup+0x24c/0x720 net/ipv6/fib6_rules.c:120
 ip6_route_output_flags_noref net/ipv6/route.c:2683 [inline]
 ip6_route_output_flags+0x1d0/0x640 net/ipv6/route.c:2695
 ip6_route_output include/net/ip6_route.h:93 [inline]
 __nf_ip6_route+0x4c/0xe0 net/ipv6/netfilter.c:113
 nf_ip6_route include/linux/netfilter_ipv6.h:111 [inline]
 synproxy_send_tcp_ipv6+0x365/0x680 net/netfilter/nf_synproxy_core.c:835
 synproxy_send_client_synack_ipv6+0x635/0x7e0 net/netfilter/nf_synproxy_core.c:897
 nft_synproxy_eval_v6 net/netfilter/nft_synproxy.c:90 [inline]
 nft_synproxy_do_eval+0x93b/0xd80 net/netfilter/nft_synproxy.c:145
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x2e9/0x1920 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x18a/0x340 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline]
 nf_hook_slow+0xbe/0x200 net/netfilter/core.c:623
 nf_hook.constprop.0+0x422/0x750 include/linux/netfilter.h:272
 NF_HOOK include/linux/netfilter.h:315 [inline]
 ip6_input+0xe0/0x2f0 net/ipv6/ip6_input.c:491
 dst_input include/net/dst.h:469 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
 NF_HOOK include/linux/netfilter.h:317 [inline]
 NF_HOOK include/linux/netfilter.h:311 [inline]
 ipv6_rcv+0x265/0x680 net/ipv6/ip6_input.c:309
 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5977
 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6090
 process_backlog+0x442/0x15e0 net/core/dev.c:6442
 __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:7414
 napi_poll net/core/dev.c:7478 [inline]
 net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605
 handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 8b 6d 02 e9 83 fb 02 00 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 43 a9 23 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c6
RAX: 0000000004488495 RBX: 0000000000000000 RCX: ffffffff8b866c99
RDX: 0000000000000000 RSI: ffffffff8de2fdb9 RDI: ffffffff8c1572e0
RBP: fffffbfff1c52ef0 R08: 0000000000000001 R09: ffffed1017086645
R10: ffff8880b843322b R11: 0000000000000001 R12: 0000000000000000
R13: ffffffff8e297780 R14: ffffffff90a93e50 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:749
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:325
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
 rest_init+0x16b/0x2b0 init/main.c:745
 start_kernel+0x3ee/0x4d0 init/main.c:1102
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
 common_startup_64+0x13e/0x148
 </TASK>