rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7172/1:b..l
	(detected by 1, t=10503 jiffies, g=27257, q=200)
task:kworker/u4:14   state:R  running task     stack:26712 pid: 7172 ppid:     2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc9000419f980 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0dba6fb97a39de00
RDX: 0000000000000000 RSI: ffffffff8a2b3a20 RDI: ffffffff8a79f980
RBP: ffffc9000419faa0 R08: dffffc0000000000 R09: 1ffffffff203a818
R10: dffffc0000000000 R11: fffffbfff203a819 R12: ffffffff8c31eaa0
R13: 1ffff92000833f3c R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 cond_resched_rcu+0xac/0x130 include/linux/sched.h:2074
 ip_vs_conn_flush net/netfilter/ipvs/ip_vs_conn.c:1393 [inline]
 ip_vs_conn_net_cleanup+0x385/0x550 net/netfilter/ipvs/ip_vs_conn.c:1475
 __ip_vs_cleanup_batch+0x6f/0xf0 net/netfilter/ipvs/ip_vs_core.c:2455
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x791/0xba0 net/core/net_namespace.c:635
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10498 jiffies! g27257 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:28016 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 7594 Comm: syz.3.939 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x843/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4b4/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__local_bh_enable_ip+0x4e/0x1c0 kernel/softirq.c:379
Code: be 00 00 00 00 00 fc ff df 48 c7 04 24 b3 8a b5 41 48 c7 44 24 08 e6 88 dd 8b 48 c7 44 24 10 30 3c 49 81 49 89 e7 49 c1 ef 03 <48> b8 f1 f1 f1 f1 f8 f3 f3 f3 4b 89 04 37 65 8b 05 35 33 b9 7e a9
RSP: 0018:ffffc9000388faa0 EFLAGS: 00000a02
RAX: f2e854c5e6a3b600 RBX: 0000000000000200 RCX: ffff88805fda5940
RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff812c61c5
RBP: ffffc9000388fb30 R08: ffff88805fda5947 R09: 1ffff1100bfb4b28
R10: dffffc0000000000 R11: ffffed100bfb4b29 R12: dffffc0000000000
R13: ffff88805fda5940 R14: dffffc0000000000 R15: 1ffff92000711f54
 fpregs_unlock arch/x86/include/asm/fpu/api.h:78 [inline]
 restore_fpregs_from_user arch/x86/kernel/fpu/signal.c:300 [inline]
 __fpu_restore_sig arch/x86/kernel/fpu/signal.c:334 [inline]
 fpu__restore_sig+0x852/0x1060 arch/x86/kernel/fpu/signal.c:466
 restore_sigcontext arch/x86/kernel/signal.c:139 [inline]
 __ia32_sys_rt_sigreturn+0x5e4/0x760 arch/x86/kernel/signal.c:674
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb49063b821
Code: 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 48 3d 01 f0 ff ff 73 01 <c3> 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:00007fff62931528 EFLAGS: 00000217
RAX: 0000000000000000 RBX: 00007fb4908b5090 RCX: 00007fb49063b819
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007fb4908b509c
RBP: 00007fb4908b5090 R08: 000000000000001d R09: 00007fb4908b4fb0
R10: 00007fb4908b4fa0 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000006 R14: 0000000000000000 R15: 00007fb4908b4fa0
 </TASK>
sched: RT throttling activated
vkms_vblank_simulate: vblank timer overrun