rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P56/3:b..l P29/3:b..l P8829/7:b..l rcu: (detected by 0, t=10502 jiffies, g=41957, q=255 ncpus=2) task:syz.1.588 state:R running task stack:24344 pid:8829 tgid:8829 ppid:7282 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x1681/0x54c0 kernel/sched/core.c:7188 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7512 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x14f/0x730 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__preempt_count_add arch/x86/include/asm/preempt.h:80 [inline] RIP: 0010:rcu_is_watching+0x9/0xb0 kernel/rcu/tree.c:751 Code: 33 03 eb cc 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 41 57 41 56 53 <65> ff 05 90 c8 c7 10 e8 ab 18 81 09 89 c3 83 f8 08 73 65 49 bf 00 RSP: 0018:ffffc90004746698 EFLAGS: 00000202 RAX: 0000000000000001 RBX: ffffffff90979301 RCX: ffff88803c24dc40 RDX: ffffc90004746701 RSI: dffffc0000000000 RDI: ffffc90004746790 RBP: dffffc0000000000 R08: ffffc900047477f0 R09: 0000000000000000 R10: ffffc900047467d8 R11: fffff520008e8cfd R12: ffffc90004747800 R13: ffffc90004740000 R14: ffffc90004746788 R15: ffffffff81770226 rcu_read_unlock include/linux/rcupdate.h:867 [inline] class_rcu_destructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0x1b76/0x2550 arch/x86/kernel/unwind_orc.c:709 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 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6246 [inline] kfree+0x1c5/0x6c0 mm/slub.c:6561 skb_kfree_head net/core/skbuff.c:1075 [inline] skb_free_head net/core/skbuff.c:1087 [inline] skb_release_data+0x828/0xa60 net/core/skbuff.c:1114 skb_release_all net/core/skbuff.c:1189 [inline] __kfree_skb+0x5d/0x210 net/core/skbuff.c:1203 tcp_v4_rcv+0x372/0x2ff0 net/ipv4/tcp_ipv4.c:2281 ip_protocol_deliver_rcu+0x221/0x440 net/ipv4/ip_input.c:207 ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:241 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6209 [inline] __netif_receive_skb net/core/dev.c:6322 [inline] process_backlog+0x569/0xc60 net/core/dev.c:6673 __napi_poll+0xab/0x550 net/core/dev.c:7737 napi_poll net/core/dev.c:7800 [inline] net_rx_action+0x696/0xe00 net/core/dev.c:7957 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:912 [inline] __dev_queue_xmit+0x1eaf/0x3900 net/core/dev.c:4905 dev_queue_xmit include/linux/netdevice.h:3401 [inline] neigh_hh_output include/net/neighbour.h:540 [inline] neigh_output include/net/neighbour.h:554 [inline] ip_finish_output2+0xcab/0x10b0 net/ipv4/ip_output.c:237 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:438 __ip_queue_xmit+0x116a/0x1bb0 net/ipv4/ip_output.c:534 __tcp_transmit_skb+0x2d62/0x4810 net/ipv4/tcp_output.c:1713 tcp_transmit_skb net/ipv4/tcp_output.c:1731 [inline] tcp_send_active_reset+0x2d1/0x5a0 net/ipv4/tcp_output.c:3868 __tcp_close+0x4c5/0x1010 net/ipv4/tcp.c:3189 tcp_close+0x28/0x110 net/ipv4/tcp.c:3316 inet_release+0x143/0x190 net/ipv4/af_inet.c:442 __sock_release net/socket.c:722 [inline] sock_close+0xc3/0x240 net/socket.c:1514 __fput+0x461/0xa70 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f007946c819 RSP: 002b:00007ffe12bd2898 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007ffe12bd2980 RCX: 00007f007946c819 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 0000000000081b1a R08: 0000000000000001 R09: 0000000000000000 R10: 0000001b33120000 R11: 0000000000000246 R12: 00007ffe12bd29c0 R13: 00007f00796e5fac R14: 0000000000081da9 R15: 00007f00796e5fa0 task:ktimers/1 state:R running task stack:23656 pid:29 tgid:29 ppid:2 task_flags:0x4208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x1681/0x54c0 kernel/sched/core.c:7188 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7512 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x14f/0x730 kernel/entry/common.c:164 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:percpu_counter_read_positive include/linux/percpu_counter.h:-1 [inline] RIP: 0010:dst_entries_get_fast include/net/dst_ops.h:48 [inline] RIP: 0010:dst_alloc+0x8c/0x170 net/core/dst.c:87 Code: db 0f 94 c0 44 84 e8 74 67 49 8d bf c0 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 74 05 e8 eb 74 2c f9 49 8b 87 c0 00 00 00 <45> 31 ed 48 85 c0 4c 0f 4f e8 49 8d 5f 04 48 89 d8 48 c1 e8 03 42 RSP: 0018:ffffc90000a3f6e0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88801d6f3d80 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff88802ade8e80 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000100 R10: dffffc0000000000 R11: ffffed1006b884de R12: ffffffff89d3b800 R13: ffffc90000a3f801 R14: dffffc0000000000 R15: ffff88802ade8dc0 ip6_dst_alloc net/ipv6/route.c:342 [inline] icmp6_dst_alloc+0x75/0x480 net/ipv6/route.c:3337 ndisc_send_skb+0x44a/0x1670 net/ipv6/ndisc.c:491 addrconf_rs_timer+0x395/0x6d0 net/ipv6/addrconf.c:4049 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 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 task:kworker/u8:3 state:R running task stack:21504 pid:56 tgid:56 ppid:2 task_flags:0x4208160 flags:0x00080000 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x1681/0x54c0 kernel/sched/core.c:7188 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7369 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 rt_mutex_wake_up_q kernel/locking/rtmutex.c:581 [inline] rt_mutex_slowunlock+0x681/0x8b0 kernel/locking/rtmutex.c:1478 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:912 [inline] __dev_queue_xmit+0x1eaf/0x3900 net/core/dev.c:4905 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:246 dst_output include/net/dst.h:470 [inline] NF_HOOK+0x177/0x4f0 include/linux/netfilter.h:318 mld_sendpack+0x8b4/0xe40 net/ipv6/mcast.c:1855 ipv6_mc_dad_complete+0x88/0x540 net/ipv6/mcast.c:2279 addrconf_dad_completed+0x622/0xe60 net/ipv6/addrconf.c:4352 addrconf_dad_work+0xdc4/0x1680 include/linux/rwlock_rt.h:-1 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 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: rcu_preempt kthread starved for 10446 jiffies! g41957 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:27704 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x1681/0x54c0 kernel/sched/core.c:7188 __schedule_loop kernel/sched/core.c:7267 [inline] schedule+0x164/0x360 kernel/sched/core.c:7282 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+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: 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 03/18/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: 2b 63 02 e9 43 c7 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 e3 ca 1e 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:ffffffff8dc07dc0 EFLAGS: 00000242 RAX: 000000000080a1a1 RBX: ffffffff819980da RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8d63094a RDI: ffffffff8ba73060 RBP: ffffffff8dc07eb0 R08: ffff8880b8833e9b R09: 1ffff110171067d3 R10: dffffc0000000000 R11: ffffed10171067d4 R12: 0000000000000000 R13: 1ffffffff1b9fdd8 R14: 0000000000000000 R15: 1ffffffff1b9fdd8 FS: 0000000000000000(0000) GS:ffff888126109000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055556d4ac4e8 CR3: 000000003dc56000 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:762 start_kernel+0x38a/0x3e0 init/main.c:1220 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