rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5924/2:b..l rcu: (detected by 1, t=10502 jiffies, g=13349, q=374 ncpus=2) task:kworker/u4:5 state:R running task stack:23920 pid:5924 ppid:2 flags:0x00004000 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 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 __local_bh_enable_ip+0x14b/0x1c0 kernel/softirq.c:413 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:856 [inline] __dev_queue_xmit+0x1b2c/0x3660 net/core/dev.c:4490 neigh_output include/net/neighbour.h:543 [inline] ip6_finish_output2+0xe3d/0x1630 net/ipv6/ip6_output.c:141 dst_output include/net/dst.h:467 [inline] NF_HOOK include/linux/netfilter.h:304 [inline] ndisc_send_skb+0xc26/0x14f0 net/ipv6/ndisc.c:513 ndisc_send_ns+0xd8/0x160 net/ipv6/ndisc.c:671 addrconf_dad_work+0xa51/0x1530 net/ipv6/addrconf.c:4264 process_one_work kernel/workqueue.c:2653 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811 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: rcu_preempt kthread starved for 10537 jiffies! g13349 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:27656 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 6023 Comm: syz.0.17 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:check_preemption_disabled+0x6/0x110 lib/smp_processor_id.c:13 Code: cc cc cc cc f3 0f 1e fa 48 c7 c7 40 8f 1c 8b 48 c7 c6 80 8f 1c 8b eb 0c 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 41 57 41 56 53 <48> 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65 8b 05 bd RSP: 0018:ffffc90000007fb8 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff88802da18ab0 RCX: b8f154b59dac0900 RDX: 0000000000000000 RSI: ffffffff8b1c8f80 RDI: ffffffff8b1c8f40 RBP: 0000000000000000 R08: ffffffff8e8b19af R09: 1ffffffff1d16335 R10: dffffc0000000000 R11: ffffc90000007ff8 R12: 0000000000000000 R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000 FS: 000055558c015500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2f963fff CR3: 000000002f6a6000 CR4: 00000000003506f0 Call Trace: irq_enter_rcu+0x62/0xf0 kernel/softirq.c:622 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0x97/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ea 97 d8 f6 48 89 df e8 a2 6c d9 f6 e8 1d 7f fd f6 fb bf 01 00 00 00 82 73 cc f6 65 8b 05 c3 a0 73 75 85 c0 74 02 5b c3 e8 40 88 70 RSP: 0018:ffffc90003937c78 EFLAGS: 00000286 RAX: b8f154b59dac0900 RBX: ffff88802c1aa500 RCX: b8f154b59dac0900 RDX: dffffc0000000000 RSI: ffffffff8acac9e0 RDI: 0000000000000001 RBP: ffff88802c1aa798 R08: ffffffff8e8b19af R09: 1ffffffff1d16335 R10: dffffc0000000000 R11: fffffbfff1d16336 R12: 1ffff110058354f3 R13: 0000000000000011 R14: dffffc0000000000 R15: 0000000000000000 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x11f5/0x13f0 kernel/signal.c:2905 arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f779fd9cdd9 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:00007ffe07b669f8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 00007f77a0015fa0 RCX: 00007f779fd9cdd9 RDX: 0000200000000240 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f779fe32d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f77a0015fac R14: 00007f77a0015fa0 R15: 00007f77a0015fa0 sched: RT throttling activated hrtimer: interrupt took 924346086 ns