rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P21785 rcu: (detected by 1, t=10502 jiffies, g=84145, q=1668 ncpus=2) task:syz.1.5863 state:R running task stack:26400 pid:21785 tgid:21784 ppid:5624 task_flags:0x400140 flags:0x00080000 Call Trace: sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:8155 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline] print_other_cpu_stall+0xfca/0x1380 kernel/rcu/tree_stall.h:681 check_cpu_stall kernel/rcu/tree_stall.h:856 [inline] rcu_pending kernel/rcu/tree.c:3679 [inline] rcu_sched_clock_irq+0x939/0x1050 kernel/rcu/tree.c:2716 update_process_times+0x234/0x2d0 kernel/time/timer.c:2475 tick_sched_handle kernel/time/tick-sched.c:298 [inline] tick_nohz_handler+0x42b/0x770 kernel/time/tick-sched.c:319 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x3bc/0xb10 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x455/0x950 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:xdp_do_redirect_frame+0x5/0x670 net/core/filter.c:4536 Code: f8 e9 0c fc ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 38 48 89 4c 24 20 48 89 54 24 RSP: 0018:ffffc90004187630 EFLAGS: 00000246 RAX: ffffffff89470c6b RBX: ffff888031b92040 RCX: ffffc90000bce000 RDX: ffff888031b92070 RSI: ffff888031b92038 RDI: ffff8880345b4000 RBP: ffffc90004187a70 R08: ffff88803e2c0000 R09: 0000000000000004 R10: 0000000000000100 R11: 0000000000000004 R12: ffff888031b92038 R13: dffffc0000000000 R14: ffffc900041878c8 R15: 0000000000000006 xdp_test_run_batch net/bpf/test_run.c:330 [inline] bpf_test_run_xdp_live+0xe34/0x1cf0 net/bpf/test_run.c:379 bpf_prog_test_run_xdp+0x81c/0x1160 net/bpf/test_run.c:1465 bpf_prog_test_run+0x2cd/0x340 kernel/bpf/syscall.c:4793 __sys_bpf+0xa20/0xd90 kernel/bpf/syscall.c:6368 __do_sys_bpf kernel/bpf/syscall.c:6469 [inline] __se_sys_bpf kernel/bpf/syscall.c:6466 [inline] __x64_sys_bpf+0xba/0xd0 kernel/bpf/syscall.c:6466 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcdcaf7ce59 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:00007fcdc91ce028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fcdcb1f5fa0 RCX: 00007fcdcaf7ce59 RDX: 0000000000000050 RSI: 0000200000000b80 RDI: 000000000000000a RBP: 00007fcdcb012d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fcdcb1f6038 R14: 00007fcdcb1f5fa0 R15: 00007fff7dc72d78 rcu: rcu_preempt kthread timer wakeup didn't happen for 10443 jiffies! g84145 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x1000 rcu: Possible timer handling issue on cpu=0 timer-softirq=49004 rcu: rcu_preempt kthread starved for 10444 jiffies! g84145 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x1000 ->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:D stack:27000 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5402 [inline] __schedule+0x16f9/0x5500 kernel/sched/core.c:7204 __schedule_loop kernel/sched/core.c:7283 [inline] schedule_rtlock+0x30/0x70 kernel/sched/core.c:7362 rtlock_slowlock_locked+0x3638/0x3c80 kernel/locking/rtmutex.c:1891 rtlock_slowlock kernel/locking/rtmutex.c:1918 [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] get_from_partial_node+0x54/0x480 mm/slub.c:3812 get_from_partial mm/slub.c:3940 [inline] ___slab_alloc+0xc2/0x930 mm/slub.c:4456 __slab_alloc_node mm/slub.c:4524 [inline] slab_alloc_node mm/slub.c:4900 [inline] kmem_cache_alloc_noprof+0xea/0x680 mm/slub.c:4919 kmem_alloc_batch lib/debugobjects.c:371 [inline] fill_pool+0x156/0x580 lib/debugobjects.c:420 debug_objects_fill_pool+0xcf/0x110 lib/debugobjects.c:752 debug_object_assert_init+0x65/0x300 lib/debugobjects.c:1030 debug_timer_assert_init kernel/time/timer.c:803 [inline] debug_assert_init kernel/time/timer.c:848 [inline] __try_to_del_timer_sync kernel/time/timer.c:1457 [inline] __timer_delete_sync+0x247/0x610 kernel/time/timer.c:1621 schedule_timeout+0x160/0x2c0 kernel/time/sleep_timeout.c:100 rcu_gp_fqs_loop+0x312/0x11b0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 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 04/18/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: 6b 61 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 93 8f 1c 00 fb f4 0c cb 03 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8dc07dc0 EFLAGS: 00000246 RAX: 000000000039aeeb RBX: ffffffff8199d71a RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8d63c144 RDI: ffffffff8ba9cd80 RBP: ffffffff8dc07eb0 R08: ffff8880b8633d5b R09: 1ffff110170c67ab R10: dffffc0000000000 R11: ffffed10170c67ac R12: 0000000000000000 R13: 1ffffffff1b9fde8 R14: 0000000000000000 R15: 1ffffffff1b9fde8 FS: 0000000000000000(0000) GS:ffff888125eec000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f20fbde6658 CR3: 000000003d954000 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+0x36a/0x5f0 kernel/sched/idle.c:352 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451 rest_init+0x2de/0x300 init/main.c:717 start_kernel+0x38a/0x3e0 init/main.c:1175 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x157