rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P8448/1:b..l rcu: (detected by 0, t=10503 jiffies, g=31889, q=1822125 ncpus=2) task:syz.4.613 state:R running task stack:23416 pid:8448 tgid:8440 ppid:5841 task_flags:0x40044c flags:0x10080002 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x1522/0x51d0 kernel/sched/core.c:6867 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7051 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] zap_pte_range mm/memory.c:1888 [inline] zap_pmd_range mm/memory.c:1950 [inline] zap_pud_range mm/memory.c:1978 [inline] zap_p4d_range mm/memory.c:1999 [inline] unmap_page_range+0x38fd/0x4030 mm/memory.c:2020 unmap_single_vma mm/memory.c:2062 [inline] unmap_vmas+0x3c0/0x5c0 mm/memory.c:2104 exit_mmap+0x251/0xb30 mm/mmap.c:1277 __mmput+0x118/0x430 kernel/fork.c:1173 exit_mm+0x168/0x220 kernel/exit.c:581 do_exit+0x62e/0x2310 kernel/exit.c:959 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112 get_signal+0x1284/0x1330 kernel/signal.c:3034 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] __do_fast_syscall_32+0x38e/0x540 arch/x86/entry/syscall_32.c:310 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf73dd539 RSP: 002b:00000000f4b7e50c EFLAGS: 00000206 ORIG_RAX: 0000000000000096 RAX: fffffffffffffffc RBX: 00000000807d8000 RCX: 0000000000800000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 230 jiffies! g31889 f0x0 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:28000 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x1522/0x51d0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0x164/0x360 kernel/sched/core.c:6964 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x1560 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:2285 kthread+0x726/0x8b0 kernel/kthread.c:463 ret_from_fork+0x51b/0xa40 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 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:its_return_thunk+0x0/0x10 arch/x86/lib/retpoline.S:417 Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e9 9b 5b 99 f5 cc RSP: 0018:ffffc90000a08978 EFLAGS: 00000246 RAX: ffffffff896c2661 RBX: 0000000000000132 RCX: 0000000000000100 RDX: ffff88801d685b80 RSI: 0000000000000132 RDI: 000000000000ffff RBP: ffffc90000a08c00 R08: ffffffff8fef2077 R09: 1ffffffff1fde40e R10: dffffc0000000000 R11: fffffbfff1fde40f R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000140 R15: ffff8881b4a21c80 FS: 0000000000000000(0000) GS:ffff8881257f3000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000800a6018 CR3: 0000000024820000 CR4: 00000000003526f0 Call Trace: skb_mac_header_was_set include/linux/skbuff.h:2981 [inline] skb_reset_mac_len include/linux/skbuff.h:2986 [inline] __netif_receive_skb_core+0x261/0x30a0 net/core/dev.c:5949 __netif_receive_skb_one_core net/core/dev.c:6150 [inline] __netif_receive_skb net/core/dev.c:6265 [inline] process_backlog+0x76d/0x1950 net/core/dev.c:6617 __napi_poll+0xae/0x340 net/core/dev.c:7681 napi_poll net/core/dev.c:7744 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7896 handle_softirqs+0x22a/0x7c0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 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+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: 98 60 02 e9 d3 e9 02 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 53 49 12 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:ffffc90000197e20 EFLAGS: 00000246 RAX: 00000000019e9371 RBX: ffffffff8199570d RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8dcc9ce4 RDI: ffffffff8c073b00 RBP: ffffc90000197f10 R08: ffff8880b87336db R09: 1ffff110170e66db R10: dffffc0000000000 R11: ffffed10170e66dc R12: ffffffff8fef2070 R13: 1ffff11003ad0b70 R14: 0000000000000001 R15: 0000000000000001 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:191 [inline] do_idle+0x1bd/0x500 kernel/sched/idle.c:332 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:430 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x147