rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P14106 rcu: (detected by 1, t=10502 jiffies, g=63665, q=2330 ncpus=2) task:syz.5.2929 state:R running task stack:24792 pid:14106 tgid:14105 ppid:11552 task_flags:0x400140 flags:0x00080000 Call Trace: sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:8181 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline] print_other_cpu_stall+0xfbf/0x1350 kernel/rcu/tree_stall.h:683 check_cpu_stall kernel/rcu/tree_stall.h:860 [inline] rcu_pending kernel/rcu/tree.c:3708 [inline] rcu_sched_clock_irq+0x93d/0x1050 kernel/rcu/tree.c:2744 update_process_times+0x234/0x2d0 kernel/time/timer.c:2475 tick_sched_handle kernel/time/tick-sched.c:296 [inline] tick_nohz_handler+0x38f/0x6b0 kernel/time/tick-sched.c:317 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x3a0/0xaf0 kernel/time/hrtimer.c:2089 hrtimer_interrupt+0x44a/0x900 kernel/time/hrtimer.c:2208 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x28/0x80 kernel/kcov.c:217 Code: 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 0d 18 47 d8 10 65 8b 35 39 47 d8 10 81 e6 00 00 ff 00 ba 00 01 00 00 23 91 fc 0b 00 00 <89> d7 09 f7 74 11 85 f6 75 39 85 d2 74 35 83 b9 14 17 00 00 00 74 RSP: 0018:ffffc90004a06db8 EFLAGS: 00000246 RAX: ffffffff891d4030 RBX: 000000000009a440 RCX: ffff88802eb65d00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000080000 RBP: ffffc90004a06f58 R08: 0000000000000000 R09: 0000000000000000 R10: ffffc90004a06d20 R11: fffff52000940da8 R12: e00000000cb275d3 R13: e00000000cb275d2 R14: 1ffffffff34d8a2c R15: e00000000cb275d2 save_dst_trace_buffer+0x1e0/0x5b0 net/core/dst.c:104 dst_release+0x28/0x1b0 net/core/dst.c:250 refdst_drop include/net/dst.h:286 [inline] skb_dst_drop include/net/dst.h:298 [inline] skb_release_head_state+0x71/0x360 net/core/skbuff.c:1165 skb_release_all net/core/skbuff.c:1189 [inline] __kfree_skb+0x24/0x210 net/core/skbuff.c:1205 vti_tunnel_xmit+0x111e/0x1a60 net/ipv4/ip_vti.c:-1 __netdev_start_xmit include/linux/netdevice.h:5415 [inline] netdev_start_xmit include/linux/netdevice.h:5424 [inline] xmit_one net/core/dev.c:3890 [inline] dev_hard_start_xmit+0x2df/0x870 net/core/dev.c:3906 __dev_queue_xmit+0x14d2/0x3880 net/core/dev.c:4879 dev_queue_xmit include/linux/netdevice.h:3452 [inline] __bpf_tx_skb net/core/filter.c:2156 [inline] __bpf_redirect_no_mac net/core/filter.c:2186 [inline] __bpf_redirect+0xaa0/0x1380 net/core/filter.c:2209 ____bpf_clone_redirect net/core/filter.c:2497 [inline] bpf_clone_redirect+0x319/0x4b0 net/core/filter.c:2460 bpf_prog_69c2527fbc57d46b+0x5f/0x68 bpf_dispatcher_nop_func include/linux/bpf.h:1454 [inline] __bpf_prog_run include/linux/filter.h:724 [inline] bpf_prog_run include/linux/filter.h:731 [inline] bpf_test_run+0x354/0x830 net/bpf/test_run.c:422 bpf_prog_test_run_skb+0xe35/0x2230 net/bpf/test_run.c:1225 bpf_prog_test_run+0x2cb/0x340 kernel/bpf/syscall.c:4859 __sys_bpf+0xa22/0xd90 kernel/bpf/syscall.c:6436 __do_sys_bpf kernel/bpf/syscall.c:6537 [inline] __se_sys_bpf kernel/bpf/syscall.c:6534 [inline] __x64_sys_bpf+0xba/0xd0 kernel/bpf/syscall.c:6534 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7eff1fc9de59 Code: ff c3 66 2e 0f 1f 84 00 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 RSP: 002b:00007eff1def6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007eff1ff25fa0 RCX: 00007eff1fc9de59 RDX: 0000000000000050 RSI: 0000200000002300 RDI: 000000000000000a RBP: 00007eff1fd33e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007eff1ff26038 R14: 00007eff1ff25fa0 R15: 00007ffff1c9e108 rcu: rcu_preempt kthread timer wakeup didn't happen for 10440 jiffies! g63665 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=26516 rcu: rcu_preempt kthread starved for 10441 jiffies! g63665 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27176 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x1709/0x5530 kernel/sched/core.c:7231 __schedule_loop kernel/sched/core.c:7308 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7323 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11c0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 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 syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: 2b 70 02 c3 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 d3 8c 26 00 fb f4 cc cf 03 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8de07ca0 EFLAGS: 00000242 RAX: 00000000002bb1df RBX: ffffffff8199442c RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8d87d8ed RDI: ffffffff8bca5e80 RBP: ffffffff8de07d78 R08: ffff8880b8633d5b R09: 1ffff110170c67ab R10: dffffc0000000000 R11: ffffed10170c67ac R12: 0000000000000000 R13: 1ffffffff1bdedf0 R14: 1ffffffff1bc0f9c R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888125c4a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3777236038 CR3: 000000000dfb0000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:767 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:768 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x1cc/0x540 kernel/sched/idle.c:355 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454 rest_init+0x378/0x3a0 init/main.c:723 start_kernel+0x392/0x3e0 init/main.c:1181 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x137/0x1b0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x157