rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (1 GPs behind) idle=9bb4/1/0x4000000000000000 softirq=29139/29140 fqs=1993 rcu: hardirqs softirqs csw/system rcu: number: 963699 0 0 rcu: cputime: 11196 29437 53 ==> 40640(ms) rcu: (t=10500 jiffies g=39821 q=1767 ncpus=2) rcu: rcu_preempt kthread timer wakeup didn't happen for 226 jiffies! g39821 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=16432 rcu: rcu_preempt kthread starved for 232 jiffies! g39821 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:27368 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 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+0x313/0x1590 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:trylock_clear_pending kernel/locking/qspinlock_paravirt.h:121 [inline] RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:435 [inline] RIP: 0010:__pv_queued_spin_lock_slowpath+0x53c/0x9d0 kernel/locking/qspinlock.c:511 Code: 10 42 0f b6 04 38 84 c0 0f 85 1b 01 00 00 48 8b 44 24 08 c6 00 01 41 bd 00 80 ff ff eb 07 f3 90 41 ff c5 74 47 43 0f b6 04 3e <84> c0 75 2b 80 3b 00 75 eb 48 89 df be 02 00 00 00 e8 1e 72 50 f7 RSP: 0018:ffffc900001f09c0 EFLAGS: 00000282 RAX: 0000000000000000 RBX: ffff888076a48cd8 RCX: ffff88801c263c00 RDX: 0000000000000100 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0 RBP: ffffc900001f0ab0 R08: ffffffff911c15c7 R09: 1ffffffff22382b8 R10: dffffc0000000000 R11: fffffbfff22382b9 R12: 1ffff110171e0001 R13: 00000000ffffc129 R14: 1ffff1100ed4919b R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056115c0cd608 CR3: 0000000074d99000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: 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/0x2c0 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+0x542/0x800 kernel/time/timer.c:2023 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036 handle_softirqs+0x280/0x820 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: 40 22 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 c3 29 43 00 fb f4 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80 RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6 RAX: 562360666f85e800 RBX: ffffffff8162ac40 RCX: 562360666f85e800 RDX: 0000000000000001 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0 RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65 R10: dffffc0000000000 R11: ffffed10171e6d66 R12: 1ffff1100384c780 R13: 1ffff92000030fc8 R14: 0000000000000001 R15: dffffc0000000000 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:170 [inline] do_idle+0x1f0/0x4e0 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323 secondary_startup_64_no_verify+0x179/0x17b CPU: 0 PID: 9573 Comm: syz.0.1349 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xc0/0x120 kernel/locking/spinlock.c:194 Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 0b c9 cd f6 65 8b 05 2c f8 74 75 85 c0 74 3c 48 c7 04 24 0e 36 RSP: 0018:ffffc90000006540 EFLAGS: 00000206 RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: b3fb8209f634f000 RDX: dffffc0000000000 RSI: ffffffff8acac960 RDI: 0000000000000001 RBP: ffffc900000065c8 R08: ffffffff911c15cf R09: 1ffffffff22382b9 R10: dffffc0000000000 R11: fffffbfff22382ba R12: dffffc0000000000 R13: ffff88805c48ce00 R14: ffffffff8d7ee620 R15: 1ffff92000000ca8 FS: 00007fbe075756c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2d423ffc CR3: 000000005c348000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: __stack_depot_save+0x560/0x630 lib/stackdepot.c:439 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_set_track+0x5f/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522 ____kasan_slab_free+0x126/0x1e0 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+0xf8/0x270 mm/slub.c:3852 skb_kfree_head net/core/skbuff.c:947 [inline] skb_free_head net/core/skbuff.c:961 [inline] skb_release_data+0x60a/0x800 net/core/skbuff.c:991 skb_release_all net/core/skbuff.c:1057 [inline] __kfree_skb+0x57/0x70 net/core/skbuff.c:1071 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3444 [inline] tcp_ack+0x2114/0x6620 net/ipv4/tcp_input.c:4004 tcp_rcv_established+0xf31/0x1d20 net/ipv4/tcp_input.c:6088 tcp_v4_do_rcv+0x4ed/0xb80 net/ipv4/tcp_ipv4.c:1734 tcp_v4_rcv+0x23bf/0x2af0 net/ipv4/tcp_ipv4.c:2166 ip_protocol_deliver_rcu+0x20e/0x3f0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2ca/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+0xa4c/0xd70 net/ipv4/ip_input.c:639 ip_list_rcv+0x3f2/0x440 net/ipv4/ip_input.c:674 __netif_receive_skb_list_ptype net/core/dev.c:5677 [inline] __netif_receive_skb_list_core+0x583/0x750 net/core/dev.c:5725 __netif_receive_skb_list net/core/dev.c:5777 [inline] netif_receive_skb_list_internal+0x943/0xca0 net/core/dev.c:5868 gro_normal_list include/net/gro.h:451 [inline] gro_normal_one include/net/gro.h:464 [inline] napi_gro_complete+0x2db/0x6f0 net/core/gro.c:264 dev_gro_receive+0x19cd/0x22c0 net/core/gro.c:502 napi_gro_receive+0x381/0xb00 net/core/gro.c:605 receive_buf+0x2203/0x3820 drivers/net/virtio_net.c:1870 virtnet_receive drivers/net/virtio_net.c:2155 [inline] virtnet_poll+0x5dd/0x1280 drivers/net/virtio_net.c:2229 __napi_poll+0xc0/0x460 net/core/dev.c:6638 napi_poll net/core/dev.c:6705 [inline] net_rx_action+0x616/0xc40 net/core/dev.c:6841 handle_softirqs+0x280/0x820 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:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5255 Code: 0f 84 33 01 00 00 48 85 db 0f 85 52 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 00 54 31 09 e8 9b 23 30 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0 RSP: 0018:ffffc9000fcd7758 EFLAGS: 00000282 RAX: b3fb8209f634f000 RBX: 0000000000000000 RCX: b3fb8209f634f000 RDX: dffffc0000000000 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0 RBP: ffffc9000fcd77b0 R08: ffffffff911c15ff R09: 1ffffffff22382bf R10: dffffc0000000000 R11: fffffbfff22382c0 R12: ffff88802d74da00 R13: dffffc0000000000 R14: ffff88802be7da00 R15: ffff8880b8e3cac8 context_switch kernel/sched/core.c:5384 [inline] __schedule+0x155b/0x45a0 kernel/sched/core.c:6700 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45 smp_call_function_single+0x48d/0x5a0 kernel/smp.c:652 task_function_call kernel/events/core.c:120 [inline] perf_install_in_context+0x5be/0x920 kernel/events/core.c:2948 __do_sys_perf_event_open kernel/events/core.c:12915 [inline] __se_sys_perf_event_open+0x1836/0x1c50 kernel/events/core.c:12567 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fbe0679c799 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:00007fbe07575028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 00007fbe06a15fa0 RCX: 00007fbe0679c799 RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000140 RBP: 00007fbe06832c99 R08: 0000000000000002 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbe06a16038 R14: 00007fbe06a15fa0 R15: 00007ffe4a877ca8