rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-....: (1 GPs behind) idle=e8b4/1/0x4000000000000000 softirq=28898/28906 fqs=360 rcu: hardirqs softirqs csw/system rcu: number: 1492278 0 0 rcu: cputime: 11990 34967 40 ==> 46990(ms) rcu: (t=10504 jiffies g=33637 q=883 ncpus=2) rcu: rcu_preempt kthread timer wakeup didn't happen for 1293 jiffies! g33637 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=20954 rcu: rcu_preempt kthread starved for 1296 jiffies! g33637 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:27080 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148 Code: 4c 1d 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 43 77 3c 00 fb f4 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9 RSP: 0018:ffffc900000078b8 EFLAGS: 00000246 RAX: ffffffff813a9538 RBX: 0000000000000003 RCX: ffffffff8ce93440 RDX: 0000000000000100 RSI: ffffffff8acacb60 RDI: ffffffff8b1cfa20 RBP: ffffc90000007990 R08: ffffffff911e75c7 R09: 1ffffffff223ceb8 R10: dffffc0000000000 R11: fffffbfff223ceb9 R12: dffffc0000000000 R13: 0000000000000200 R14: 0000000000000003 R15: 1ffff92000000f1c FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffdcbcb5080 CR3: 00000000242e4000 CR4: 00000000003506f0 DR0: 0000000000000008 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] kvm_wait+0x23d/0x2a0 arch/x86/kernel/kvm.c:1058 pv_wait arch/x86/include/asm/paravirt.h:598 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x613/0x9c0 kernel/locking/qspinlock.c:511 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x23e/0x2b0 kernel/locking/spinlock_debug.c:115 spin_lock include/linux/spinlock.h:351 [inline] tcp_write_timer+0x2d/0x280 net/ipv4/tcp_timer.c:707 call_timer_fn+0x189/0x540 kernel/time/timer.c:1701 expire_timers kernel/time/timer.c:1752 [inline] __run_timers+0x570/0x810 kernel/time/timer.c:2023 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036 handle_softirqs+0x27d/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148 Code: 4c 1d 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 43 77 3c 00 fb f4 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9 RSP: 0018:ffffffff8ce07d80 EFLAGS: 000002c6 RAX: fc74eb6236245400 RBX: ffffffff81628c14 RCX: fc74eb6236245400 RDX: 0000000000000001 RSI: ffffffff8acacb60 RDI: ffffffff8b1cfa20 RBP: ffffffff8ce07eb8 R08: ffff8880b8e36bab R09: 1ffff110171c6d75 R10: dffffc0000000000 R11: ffffed10171c6d76 R12: 1ffffffff19c0fbc R13: dffffc0000000000 R14: 1ffffffff19d2688 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:178 [inline] do_idle+0x334/0x5c0 kernel/sched/idle.c:302 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401 rest_init+0x2e2/0x300 init/main.c:744 arch_call_rest_init+0xe/0x10 init/main.c:840 start_kernel+0x461/0x4e0 init/main.c:1085 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b CPU: 1 PID: 10067 Comm: syz.1.1230 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:arch_stack_walk+0x14b/0x190 arch/x86/kernel/stacktrace.c:24 Code: ff 48 89 c6 e8 06 59 54 00 4d 85 e4 74 2c 48 89 df 4c 89 e6 41 ff d6 84 c0 74 26 4c 89 ff e8 0c 93 08 00 83 bd 78 ff ff ff 00 <74> 1c e8 9e 54 54 00 eb c1 e8 97 54 54 00 eb 13 e8 90 54 54 00 eb RSP: 0018:ffffc900001eed08 EFLAGS: 00000202 RAX: ffffffff813b4101 RBX: ffffc900001eedc0 RCX: ffff88802ba43c00 RDX: 0000000000000100 RSI: 0000000000000304 RDI: 0000000000000000 RBP: ffffc900001eed90 R08: ffff88802ba43c00 R09: 0000000000000003 R10: 0000000000000004 R11: 0000000000000100 R12: ffffffff81758b8a R13: ffffc900001ef128 R14: ffffffff81758be0 R15: ffffc900001eed08 FS: 00007ff8492c66c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000100000000 CR3: 000000002b477000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000200000000300 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1811 [inline] slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837 slab_free mm/slub.c:3830 [inline] __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843 skb_kfree_head net/core/skbuff.c:946 [inline] skb_free_head net/core/skbuff.c:958 [inline] skb_release_data+0x609/0x7f0 net/core/skbuff.c:988 skb_release_all net/core/skbuff.c:1054 [inline] __kfree_skb net/core/skbuff.c:1068 [inline] kfree_skb_reason+0x10e/0x170 net/core/skbuff.c:1104 dev_kfree_skb_any_reason+0x120/0x130 net/core/dev.c:3241 free_old_xmit_skbs+0x11a/0x3b0 drivers/net/virtio_net.c:780 start_xmit+0x16d/0x1470 drivers/net/virtio_net.c:2420 __netdev_start_xmit include/linux/netdevice.h:4943 [inline] netdev_start_xmit include/linux/netdevice.h:4957 [inline] xmit_one net/core/dev.c:3644 [inline] dev_hard_start_xmit+0x269/0x790 net/core/dev.c:3660 sch_direct_xmit+0x251/0x4a0 net/sched/sch_generic.c:345 __dev_xmit_skb net/core/dev.c:3881 [inline] __dev_queue_xmit+0x162a/0x3630 net/core/dev.c:4416 dev_queue_xmit include/linux/netdevice.h:3113 [inline] neigh_hh_output include/net/neighbour.h:527 [inline] neigh_output include/net/neighbour.h:541 [inline] ip_finish_output2+0xd4f/0x1260 net/ipv4/ip_output.c:235 NF_HOOK_COND include/linux/netfilter.h:293 [inline] ip_output+0x2a5/0x3a0 net/ipv4/ip_output.c:436 dst_output include/net/dst.h:467 [inline] ip_local_out net/ipv4/ip_output.c:129 [inline] __ip_queue_xmit+0x1056/0x1960 net/ipv4/ip_output.c:540 __tcp_transmit_skb+0x1dd6/0x3470 net/ipv4/tcp_output.c:1427 tcp_validate_incoming+0xf37/0x22b0 net/ipv4/tcp_input.c:5901 tcp_rcv_established+0x7e1/0x1d70 net/ipv4/tcp_input.c:6166 tcp_v4_do_rcv+0x6d3/0xba0 net/ipv4/tcp_ipv4.c:1735 tcp_v4_rcv+0x2358/0x2a60 net/ipv4/tcp_ipv4.c:2167 ip_protocol_deliver_rcu+0x20a/0x3f0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2c3/0x510 net/ipv4/ip_input.c:233 NF_HOOK+0x32d/0x3b0 include/linux/netfilter.h:304 dst_input include/net/dst.h:477 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:580 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:631 [inline] ip_sublist_rcv+0xa36/0xd60 net/ipv4/ip_input.c:639 ip_list_rcv+0x3ed/0x440 net/ipv4/ip_input.c:674 __netif_receive_skb_list_ptype net/core/dev.c:5689 [inline] __netif_receive_skb_list_core+0x582/0x770 net/core/dev.c:5737 __netif_receive_skb_list net/core/dev.c:5789 [inline] netif_receive_skb_list_internal+0x943/0xca0 net/core/dev.c:5880 gro_normal_list include/net/gro.h:451 [inline] gro_normal_one include/net/gro.h:464 [inline] napi_gro_complete+0x2df/0x6f0 net/core/gro.c:269 dev_gro_receive+0x1987/0x22a0 net/core/gro.c:507 napi_gro_receive+0x376/0xaf0 net/core/gro.c:610 receive_buf+0x219d/0x37a0 drivers/net/virtio_net.c:1870 virtnet_receive drivers/net/virtio_net.c:2155 [inline] virtnet_poll+0x60e/0x11e0 drivers/net/virtio_net.c:2229 __napi_poll+0xbb/0x460 net/core/dev.c:6650 napi_poll net/core/dev.c:6717 [inline] net_rx_action+0x65f/0xcc0 net/core/dev.c:6853 handle_softirqs+0x27d/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:preempt_schedule_irq+0xba/0x150 kernel/sched/core.c:7010 Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 6f bf 01 00 00 00 e8 51 51 c8 f6 e8 9c 3c f9 f6 fb bf 01 00 00 00 31 b4 ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f RSP: 0018:ffffc90003847a40 EFLAGS: 00000286 RAX: d9f893c36ccc0a00 RBX: ffff88802ba43c00 RCX: d9f893c36ccc0a00 RDX: dffffc0000000000 RSI: ffffffff8acacb60 RDI: 0000000000000001 RBP: ffffc90003847af0 R08: ffffffff8e8c6b2f R09: 1ffffffff1d18d65 R10: dffffc0000000000 R11: fffffbfff1d18d66 R12: 0000000000000000 R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000708f48 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:preempt_schedule+0x0/0xd0 kernel/sched/core.c:6884 Code: 4c 89 f7 e8 22 4a 4b f7 eb af 66 0f 1f 00 bf 01 00 00 00 e8 52 56 c8 f6 e8 fd fd ff ff bf 01 00 00 00 e8 a3 54 c8 f6 c3 66 90 0f 1e fa 55 48 89 e5 41 56 53 48 83 e4 e0 48 83 ec 60 65 48 8b RSP: 0018:ffffc90003847bb0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffc90000a23508 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000ffffffff RBP: ffffc90003847c00 R08: ffffc90000a2350b R09: 1ffff920001446a1 R10: dffffc0000000000 R11: fffff520001446a2 R12: dffffc0000000000 R13: ffffc90000a23548 R14: 0000000000000001 R15: ffffc900037dfc50 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] futex_wake+0x41d/0x4f0 kernel/futex/waitwake.c:183 do_futex+0x35d/0x3e0 kernel/futex/syscalls.c:139 __do_sys_futex kernel/futex/syscalls.c:211 [inline] __se_sys_futex+0x3a9/0x440 kernel/futex/syscalls.c:192 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7ff84839de59 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:00007ff8492c60e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00007ff848625fa8 RCX: 00007ff84839de59 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007ff848625fac RBP: 00007ff848625fa0 R08: 0000000000745ae6 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff848626038 R14: 00007ffcf5953c10 R15: 00007ffcf5953cf8