rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P29/2:b..l P11868 rcu: (detected by 1, t=10502 jiffies, g=32157, q=752 ncpus=2) task:syz.5.1748 state:R running task stack:25216 pid:11868 tgid:11867 ppid:7848 task_flags:0x400140 flags:0x00080000 Call Trace: sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:7865 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:2474 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:1785 [inline] __hrtimer_run_queues+0x514/0xda0 kernel/time/hrtimer.c:1849 hrtimer_interrupt+0x42d/0x1000 kernel/time/hrtimer.c:1911 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x460 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x20b/0x2e0 kernel/locking/lockdep.c:5872 Code: e9 30 ff ff ff e8 75 fd 83 09 f7 c3 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 e1 aa ae 10 48 3b 44 24 30 75 33 fb 48 83 c4 38 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 46 bd 87 09 cc 48 8d 3d be 61 cd RSP: 0018:ffffc90005c2f090 EFLAGS: 00000296 RAX: 1aae0721f4127b00 RBX: 0000000000000246 RCX: 0000000000000046 RDX: 00000000f30e1b4b RSI: ffffffff8d7c2056 RDI: ffffffff8ba67a00 RBP: 0000000000000000 R08: ffffffff81d44056 R09: ffffffff8ddcb980 R10: ffffc90005c2f238 R11: ffffffff81af8df0 R12: 0000000000000002 R13: ffffffff8ddcb980 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] class_rcu_constructor include/linux/rcupdate.h:1193 [inline] bpf_has_frame_pointer+0x46/0x390 kernel/bpf/core.c:772 orc_bpf_find arch/x86/kernel/unwind_orc.c:188 [inline] orc_find arch/x86/kernel/unwind_orc.c:253 [inline] unwind_next_frame+0x452/0x23c0 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 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4538 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_node_noprof+0x22a/0x6e0 mm/slub.c:4918 kmalloc_reserve net/core/skbuff.c:613 [inline] pskb_expand_head+0x1d9/0x1320 net/core/skbuff.c:2315 __bpf_try_make_writable net/core/filter.c:1681 [inline] bpf_try_make_writable net/core/filter.c:1687 [inline] bpf_try_make_head_writable net/core/filter.c:1695 [inline] ____bpf_clone_redirect net/core/filter.c:2487 [inline] bpf_clone_redirect+0x1ea/0x4b0 net/core/filter.c:2456 bpf_prog_9299a0b1a05450b6+0x5f/0x68 bpf_dispatcher_nop_func include/linux/bpf.h:1402 [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:423 bpf_prog_test_run_skb+0xd22/0x1c90 net/bpf/test_run.c:1159 bpf_prog_test_run+0x2cd/0x340 kernel/bpf/syscall.c:4743 __sys_bpf+0x643/0x950 kernel/bpf/syscall.c:6267 __do_sys_bpf kernel/bpf/syscall.c:6362 [inline] __se_sys_bpf kernel/bpf/syscall.c:6360 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6360 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb4dcf1c819 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:00007fb4db16e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fb4dd195fa0 RCX: 00007fb4dcf1c819 RDX: 0000000000000050 RSI: 0000200000000100 RDI: 000000000000000a RBP: 00007fb4dcfb2c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb4dd196038 R14: 00007fb4dd195fa0 R15: 00007ffd00b09548 task:ktimers/1 state:R running task stack:23424 pid:29 tgid:29 ppid:2 task_flags:0x4208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1553/0x5240 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule_rtlock+0x30/0x70 kernel/sched/core.c:7072 rtlock_slowlock_locked+0x3638/0x3c80 kernel/locking/rtmutex.c:1868 rtlock_slowlock kernel/locking/rtmutex.c:1895 [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:3252 [inline] rmqueue mm/page_alloc.c:3424 [inline] get_page_from_freelist+0xd9f/0x2950 mm/page_alloc.c:3959 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab+0x77/0x660 mm/slub.c:3481 new_slab mm/slub.c:3539 [inline] refill_objects+0x334/0x3c0 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x35c/0x710 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] kmem_cache_alloc_node_noprof+0x4f4/0x6e0 mm/slub.c:4918 kmalloc_reserve net/core/skbuff.c:613 [inline] __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713 alloc_skb include/linux/skbuff.h:1383 [inline] wg_packet_send_keepalive+0x65/0x2c0 drivers/net/wireguard/send.c:226 call_timer_fn+0x192/0x640 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2373 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2385 run_timer_base kernel/time/timer.c:2394 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1138 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread timer wakeup didn't happen for 10467 jiffies! g32157 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=24885 rcu: rcu_preempt kthread starved for 10468 jiffies! g32157 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:25248 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1553/0x5240 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0x164/0x360 kernel/sched/core.c:7008 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 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+0x51e/0xb90 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 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: 5e 5c 02 e9 13 c4 03 00 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 f3 3c 25 00 fb f4 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8da07dc0 EFLAGS: 00000242 RAX: 00000000008f3d3d RBX: ffffffff81996cba RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8d565a2d RDI: ffffffff8ba67a00 RBP: ffffffff8da07eb0 R08: ffff8880b8833e1b R09: 1ffff110171067c3 R10: dffffc0000000000 R11: ffffed10171067c4 R12: 0000000000000000 R13: 1ffffffff1b605d8 R14: 0000000000000000 R15: 1ffffffff1b605d8 FS: 0000000000000000(0000) GS:ffff888126332000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000008038 CR3: 0000000081e08000 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:760 start_kernel+0x385/0x3d0 init/main.c:1210 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/0x147