rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10521 ticks this GP) idle=616c/1/0x4000000000000000 softirq=99587/99589 fqs=212
rcu: 	(t=10502 jiffies g=83817 q=104 ncpus=2)
rcu: rcu_preempt kthread starved for 8994 jiffies! g83817 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:27192 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 53 e7 02 00 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 73 67 0e 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000197de0 EFLAGS: 000002c2
RAX: 0288f239f5c03a00 RBX: ffffffff819683c8 RCX: 0288f239f5c03a00
RDX: 0000000000000001 RSI: ffffffff8d9b8241 RDI: ffffffff8be33880
RBP: ffffc90000197f20 R08: ffff8880b8732f9b R09: 1ffff110170e65f3
R10: dffffc0000000000 R11: ffffed10170e65f4 R12: ffffffff8fa39030
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff110039d5b40
FS:  0000000000000000(0000) GS:ffff888125d18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0f10866c48 CR3: 0000000058db6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x1e8/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x147
 </TASK>
CPU: 0 UID: 0 PID: 15013 Comm: syz.0.2274 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:fq_pband_head_select net/sched/sch_fq.c:-1 [inline]
RIP: 0010:fq_dequeue+0x816/0x2650 net/sched/sch_fq.c:675
Code: 4d 89 e6 eb 28 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 f9 dd 8a f8 48 83 3b 00 0f 84 a3 09 00 00 e8 ca 6f 27 f8 <49> 89 de 4d 89 f7 49 c1 ef 03 43 80 3c 2f 00 74 08 4c 89 f7 e8 d1
RSP: 0018:ffffc90000006f20 EFLAGS: 00000246
RAX: ffffffff89983e46 RBX: ffff88807be4c348 RCX: ffff888027388000
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000004
RBP: ffffc900000070b0 R08: ffffffff8fa39037 R09: 1ffffffff1f47206
R10: dffffc0000000000 R11: ffffffff8167ba50 R12: ffff88807be4c338
R13: dffffc0000000000 R14: ffff88807be4c358 R15: 0000000000000001
FS:  00007ff40a5526c0(0000) GS:ffff888125c18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000018d030 CR3: 000000005ef02000 CR4: 00000000003526f0
DR0: 0000040000000000 DR1: 000000000000064f DR2: 0000000000000002
DR3: 0000000040000006 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 dequeue_skb net/sched/sch_generic.c:294 [inline]
 qdisc_restart net/sched/sch_generic.c:399 [inline]
 __qdisc_run+0x23c/0x15f0 net/sched/sch_generic.c:417
 __dev_xmit_skb net/core/dev.c:4183 [inline]
 __dev_queue_xmit+0x1056/0x3b50 net/core/dev.c:4691
 dev_queue_xmit include/linux/netdevice.h:3361 [inline]
 neigh_hh_output include/net/neighbour.h:531 [inline]
 neigh_output include/net/neighbour.h:545 [inline]
 ip_finish_output2+0xd03/0x1160 net/ipv4/ip_output.c:235
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip_output+0x2a1/0x3c0 net/ipv4/ip_output.c:436
 ip_local_out net/ipv4/ip_output.c:129 [inline]
 ip_send_skb net/ipv4/ip_output.c:1506 [inline]
 ip_push_pending_frames+0xbe/0x150 net/ipv4/ip_output.c:1526
 __icmp_send+0xf87/0x12d0 net/ipv4/icmp.c:783
 ipv4_send_dest_unreach net/ipv4/route.c:1249 [inline]
 ipv4_link_failure+0x64e/0xa30 net/ipv4/route.c:1256
 dst_link_failure include/net/dst.h:429 [inline]
 arp_error_report+0x115/0x160 net/ipv4/arp.c:296
 neigh_invalidate+0x235/0x460 net/core/neighbour.c:1082
 neigh_timer_handler+0x949/0x1150 net/core/neighbour.c:1173
 call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747
 expire_timers kernel/time/timer.c:1798 [inline]
 __run_timers kernel/time/timer.c:2372 [inline]
 __run_timer_base+0x61a/0x860 kernel/time/timer.c:2384
 run_timer_base kernel/time/timer.c:2393 [inline]
 run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0xca/0x1f0 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+0xa6/0xc0 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 eb f9 4a f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 53 9f 13 f6 65 8b 05 0c 22 24 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc90004927500 EFLAGS: 00000206
RAX: 2ab977935da6ba00 RBX: 0000000000000a06 RCX: 2ab977935da6ba00
RDX: 0000000000000006 RSI: ffffffff8d9b8241 RDI: 0000000000000001
RBP: ffffc90004927598 R08: ffffffff8fa39037 R09: 1ffffffff1f47206
R10: dffffc0000000000 R11: fffffbfff1f47207 R12: dffffc0000000000
R13: 1ffff92000924ecb R14: ffff888066eb5380 R15: 1ffff92000924ea0
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 prepare_to_wait_exclusive+0xe7/0x240 kernel/sched/wait.c:275
 unix_wait_for_peer+0xfc/0x2e0 net/unix/af_unix.c:1630
 unix_dgram_sendmsg+0xb7a/0x1850 net/unix/af_unix.c:2273
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x219/0x270 net/socket.c:729
 ____sys_sendmsg+0x52d/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmmsg+0x227/0x430 net/socket.c:2757
 __do_sys_sendmmsg net/socket.c:2784 [inline]
 __se_sys_sendmmsg net/socket.c:2781 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2781
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff40978ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff40a552038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007ff4099c5fa0 RCX: 00007ff40978ebe9
RDX: 0000000000000318 RSI: 00002000000bd000 RDI: 0000000000000004
RBP: 00007ff409811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff4099c6038 R14: 00007ff4099c5fa0 R15: 00007ff409aefa28
 </TASK>
sched: DL replenish lagged too much