rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7505 P16/2:b..l rcu: (detected by 0, t=10502 jiffies, g=19269, q=6397 ncpus=2) task:ktimers/0 state:R running task stack:23704 pid:16 tgid:16 ppid:2 task_flags:0x4208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x16dc/0x5500 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule_rtlock+0x30/0x70 kernel/sched/core.c:7386 rtlock_slowlock_locked+0x35c5/0x3c20 kernel/locking/rtmutex.c:1895 rtlock_slowlock kernel/locking/rtmutex.c:1922 [inline] rtlock_lock kernel/locking/spinlock_rt.c:43 [inline] __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline] rt_spin_lock+0x165/0x400 kernel/locking/spinlock_rt.c:57 spin_lock include/linux/spinlock_rt.h:45 [inline] rmqueue_buddy mm/page_alloc.c:3223 [inline] rmqueue mm/page_alloc.c:3415 [inline] get_page_from_freelist+0xcc4/0x26a0 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304 alloc_slab_page mm/slub.c:3289 [inline] allocate_slab+0x74/0x5d0 mm/slub.c:3404 new_slab mm/slub.c:3447 [inline] refill_objects+0x32b/0x3c0 mm/slub.c:7241 refill_sheaf mm/slub.c:2827 [inline] __pcs_replace_empty_main+0x335/0x6a0 mm/slub.c:4692 alloc_from_pcs mm/slub.c:4790 [inline] slab_alloc_node mm/slub.c:4924 [inline] kmem_cache_alloc_node_noprof+0x4ff/0x710 mm/slub.c:4991 kmalloc_reserve net/core/skbuff.c:615 [inline] __alloc_skb+0x276/0x7a0 net/core/skbuff.c:715 alloc_skb include/linux/skbuff.h:1386 [inline] wg_packet_send_keepalive+0x65/0x2c0 drivers/net/wireguard/send.c:226 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x67b/0x9b0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160 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 task:syz.0.541 state:R running task stack:23864 pid:7505 tgid:7498 ppid:5605 task_flags:0x400140 flags:0x00080000 Call Trace: sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:8180 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline] print_other_cpu_stall+0xf7b/0x1310 kernel/rcu/tree_stall.h:680 check_cpu_stall kernel/rcu/tree_stall.h:855 [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:2096 hrtimer_interrupt+0x44a/0x900 kernel/time/hrtimer.c:2215 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 c8 c4 a8 10 65 8b 35 e9 c4 a8 10 81 e6 00 00 ff 00 ba 00 01 00 00 23 91 f4 0b 00 00 <89> d7 09 f7 74 11 85 f6 75 39 85 d2 74 35 83 b9 04 17 00 00 00 74 RSP: 0000:ffffc90020516af0 EFLAGS: 00000246 RAX: ffffffff81d55c03 RBX: 0000000000000000 RCX: ffff888027311f00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000 R10: ffffc90020516c38 R11: ffffffff81afe1e0 R12: ffff88803b3a11f0 R13: 000000000000001b R14: ffffffffa0206ef2 R15: 0000000000000002 bpf_has_frame_pointer+0x253/0x390 kernel/bpf/core.c:777 orc_bpf_find arch/x86/kernel/unwind_orc.c:188 [inline] orc_find arch/x86/kernel/unwind_orc.c:253 [inline] unwind_next_frame+0x436/0x2550 arch/x86/kernel/unwind_orc.c:510 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2700 [inline] slab_free mm/slub.c:6310 [inline] kmem_cache_free+0x187/0x6c0 mm/slub.c:6437 vti_tunnel_xmit+0x1111/0x1a50 net/ipv4/ip_vti.c:-1 __netdev_start_xmit include/linux/netdevice.h:5387 [inline] netdev_start_xmit include/linux/netdevice.h:5396 [inline] xmit_one net/core/dev.c:3889 [inline] dev_hard_start_xmit+0x2df/0x870 net/core/dev.c:3905 __dev_queue_xmit+0x1549/0x3890 net/core/dev.c:4872 dev_queue_xmit include/linux/netdevice.h:3436 [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:723 [inline] bpf_prog_run include/linux/filter.h:730 [inline] bpf_test_run+0x354/0x830 net/bpf/test_run.c:422 bpf_prog_test_run_skb+0xe35/0x2230 net/bpf/test_run.c:1229 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: 0033:0x7f68670ece59 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:00007f68652fc028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f6867366180 RCX: 00007f68670ece59 RDX: 0000000000000050 RSI: 0000200000002300 RDI: 000000000000000a RBP: 00007f6867182e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6867366218 R14: 00007f6867366180 R15: 00007ffc19f00dd8 rcu: rcu_preempt kthread timer wakeup didn't happen for 10364 jiffies! g19269 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=9434 rcu: rcu_preempt kthread starved for 10365 jiffies! g19269 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28184 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x16dc/0x5500 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0x164/0x360 kernel/sched/core.c:7322 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP 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: 1b 6c 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 33 42 28 00 fb f4 8c cd 03 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0000:ffffc900001d7e40 EFLAGS: 00000246 RAX: ffff888126244000 RBX: ffffffff8199431c RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8ba7f080 RDI: ffffffff8199431c RBP: ffffc900001d7f10 R08: ffff8880b8933d5b R09: 1ffff110171267ab R10: dffffc0000000000 R11: ffffed10171267ac R12: 0000000000000000 R13: 1ffff11003a51000 R14: 1ffff9200003afd0 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888126244000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f21aa7ef4ff CR3: 000000003b7ec000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:766 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:767 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 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x157