rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=14085, q=1486 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10494 (4294964439-4294953945), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10494 jiffies! g14085 f0x2 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:27728 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5258 [inline] __schedule+0x150e/0x5070 kernel/sched/core.c:6866 __schedule_loop kernel/sched/core.c:6948 [inline] schedule+0x165/0x360 kernel/sched/core.c:6963 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+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 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 10/25/2025 RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x2f/0x70 kernel/kcov.c:217 Code: 8b 04 24 65 48 8b 0c 25 08 40 c4 92 65 8b 15 b8 47 02 11 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 6c 16 00 00 00 <74> 2c 8b 91 48 16 00 00 83 fa 02 75 21 48 8b 91 50 16 00 00 48 8b RSP: 0018:ffffc90000a08458 EFLAGS: 00000246 RAX: ffffffff89453544 RBX: 0000000000000001 RCX: ffff88801d6e5b80 RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000008 RBP: 0000000000000500 R08: ffffffff8fc3d077 R09: 1ffffffff1f87a0e R10: dffffc0000000000 R11: fffffbfff1f87a0f R12: ffff88806bb0a883 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff888058747500 FS: 0000000000000000(0000) GS:ffff888125adc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbbbe88cd58 CR3: 000000001effe000 CR4: 00000000003526f0 Call Trace: cpu_max_bits_warn include/linux/cpumask.h:138 [inline] cpumask_check include/linux/cpumask.h:145 [inline] cpumask_test_cpu include/linux/cpumask.h:649 [inline] cpu_online include/linux/cpumask.h:1231 [inline] trace_netif_rx_exit+0x34/0x1d0 include/trace/events/net.h:319 __netif_rx+0x81/0xc0 net/core/dev.c:5669 veth_forward_skb drivers/net/veth.c:321 [inline] veth_xmit+0x57a/0xd50 drivers/net/veth.c:375 __netdev_start_xmit include/linux/netdevice.h:5288 [inline] netdev_start_xmit include/linux/netdevice.h:5297 [inline] xmit_one net/core/dev.c:3854 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3870 __dev_queue_xmit+0x1493/0x3140 net/core/dev.c:4818 dev_queue_xmit include/linux/netdevice.h:3387 [inline] hsr_xmit net/hsr/hsr_forward.c:440 [inline] hsr_forward_do net/hsr/hsr_forward.c:581 [inline] hsr_forward_skb+0x158b/0x2860 net/hsr/hsr_forward.c:743 send_hsr_supervision_frame+0x731/0xcb0 net/hsr/hsr_device.c:364 hsr_announce+0x1d5/0x360 net/hsr/hsr_device.c:421 call_timer_fn+0x16e/0x590 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2373 [inline] __run_timer_base+0x61a/0x860 kernel/time/timer.c:2385 run_timer_base kernel/time/timer.c:2394 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2404 handle_softirqs+0x27d/0x850 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:727 irq_exit_rcu+0x9/0x30 kernel/softirq.c:743 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: cc cc cc cc 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 33 0e 21 00 f3 0f 1e fa fb f4 48 ee 02 00 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000197de0 EFLAGS: 000002c6 RAX: 4e5ae46a8974b100 RBX: ffffffff8197c6ba RCX: 4e5ae46a8974b100 RDX: 0000000000000001 RSI: ffffffff8daa9dc3 RDI: ffffffff8be247e0 RBP: ffffc90000197f10 R08: ffff8880b87336db R09: 1ffff110170e66db R10: dffffc0000000000 R11: ffffed10170e66dc R12: ffffffff8fc3d070 R13: 1ffff11003adcb70 R14: 0000000000000001 R15: 0000000000000001 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x1ea/0x520 kernel/sched/idle.c:332 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x147