rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6023/1:b..l rcu: (detected by 0, t=10503 jiffies, g=15717, q=592 ncpus=2) task:syz-executor state:R running task stack:21736 pid:6023 ppid:6014 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45 vprintk_emit+0x578/0x600 kernel/printk/printk.c:2342 dev_vprintk_emit+0x338/0x3e0 drivers/base/core.c:4953 dev_printk_emit+0xe1/0x130 drivers/base/core.c:4964 __netdev_printk+0x3bf/0x4a0 net/core/dev.c:11482 netdev_info+0x10b/0x160 net/core/dev.c:11537 nsim_udp_tunnel_set_port+0x297/0x440 drivers/net/netdevsim/udp_tunnels.c:34 udp_tunnel_nic_device_sync_one net/ipv4/udp_tunnel_nic.c:-1 [inline] udp_tunnel_nic_device_sync_by_port net/ipv4/udp_tunnel_nic.c:246 [inline] __udp_tunnel_nic_device_sync+0xa70/0x1370 net/ipv4/udp_tunnel_nic.c:289 udp_tunnel_nic_device_sync net/ipv4/udp_tunnel_nic.c:312 [inline] __udp_tunnel_nic_add_port+0xaf8/0xdb0 net/ipv4/udp_tunnel_nic.c:531 udp_tunnel_nic_add_port include/net/udp_tunnel.h:333 [inline] udp_tunnel_notify_add_rx_port+0x28e/0x3e0 net/ipv4/udp_tunnel_core.c:127 geneve_socket_create drivers/net/geneve.c:614 [inline] geneve_sock_add+0x55e/0x910 drivers/net/geneve.c:689 geneve_open+0xd2/0x140 drivers/net/geneve.c:731 __dev_open+0x2bc/0x430 net/core/dev.c:1506 __dev_change_flags+0x20e/0x6a0 net/core/dev.c:8685 dev_change_flags+0x88/0x1a0 net/core/dev.c:8757 do_setlink+0xc74/0x3fb0 net/core/rtnetlink.c:2905 __rtnl_newlink net/core/rtnetlink.c:3703 [inline] rtnl_newlink+0x175b/0x2020 net/core/rtnetlink.c:3750 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6472 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] __sys_sendto+0x46a/0x620 net/socket.c:2201 __do_sys_sendto net/socket.c:2213 [inline] __se_sys_sendto net/socket.c:2209 [inline] __x64_sys_sendto+0xde/0xf0 net/socket.c:2209 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f1b66d915dc RSP: 002b:00007ffc9c3f1710 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f1b67b14620 RCX: 00007f1b66d915dc RDX: 000000000000002c RSI: 00007f1b67b14670 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffc9c3f1764 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003 R13: 0000000000000000 R14: 00007f1b67b14670 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10553 jiffies! g15717 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:27752 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 6233 Comm: syz.4.21 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline] RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline] RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline] RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline] RIP: 0010:native_apic_msr_write+0x39/0x50 arch/x86/include/asm/apic.h:196 Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 f3 0f 1e fa 89 f6 31 d2 e9 f7 36 19 03 0f 1f 80 00 00 00 RSP: 0018:ffffc900001f0e58 EFLAGS: 00000046 RAX: 0000000000072a99 RBX: ffff8880b8f28280 RCX: 0000000000000838 RDX: 0000000000000000 RSI: 0000000000072a99 RDI: 0000000000000838 RBP: 0000000000000000 R08: ffffffff8e4a212f R09: 1ffffffff1c94425 R10: dffffc0000000000 R11: fffffbfff1c94426 R12: dffffc0000000000 R13: 000000000ffffe52 R14: 0000000000072a99 R15: 0000000000000020 FS: 000055558bfe7500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b34263fff CR3: 0000000023731000 CR4: 00000000003506e0 Call Trace: apic_write arch/x86/include/asm/apic.h:404 [inline] lapic_next_event+0x11/0x20 arch/x86/kernel/apic/apic.c:448 clockevents_program_event+0x1c0/0x310 kernel/time/clockevents.c:334 hrtimer_interrupt+0x5a1/0x9c0 kernel/time/hrtimer.c:1889 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline] __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 6a 5f f6 f6 48 89 df e8 82 31 f7 f6 e8 5d d8 1a f7 fb bf 01 00 00 00 52 53 ea f6 65 8b 05 43 9a 92 75 85 c0 74 02 5b c3 e8 20 80 8f RSP: 0018:ffffc90003407c78 EFLAGS: 00000286 RAX: 272697b2a23ff300 RBX: ffff88802db7ae40 RCX: 272697b2a23ff300 RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001 RBP: ffff88802db7b0d8 R08: ffffffff8e4a212f R09: 1ffffffff1c94425 R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 1ffff11005b6f61b R13: 0000000000000011 R14: dffffc0000000000 R15: 0000000000000000 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x11f5/0x1400 kernel/signal.c:2905 arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb11438f749 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:00007ffc582feb08 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 00007fb1145e5fa0 RCX: 00007fb11438f749 RDX: 0000200000000240 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fb114413f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb1145e5fa0 R14: 00007fb1145e5fa0 R15: 0000000000000004 sched: RT throttling activated