rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=f2a4/1/0x4000000000000000 softirq=12024/12025 fqs=35 rcu: (detected by 1, t=10506 jiffies, g=10297, q=118 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 11 Comm: kworker/u4:0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: netns cleanup_net RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:65 Code: 48 89 da e8 f2 9d f4 ff 48 8b 74 24 30 48 c7 c7 00 70 fc 8a e8 e1 9d f4 ff e8 fc 7e ff ff eb a8 e8 c5 e8 ff ff 0f 1f 44 00 00 0f 1e fa 48 89 fe 48 c7 c7 80 6f fc 8a e9 dd fe ff ff cc cc cc RSP: 0018:ffffc90000007c20 EFLAGS: 00000046 RAX: 0000000000000001 RBX: ffff88801ba4bc00 RCX: 0000000000000001 RDX: ffff88801ba4bc00 RSI: ffff88802c0ce300 RDI: ffffffff8aaace60 RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000000f7c R12: 0000000000000005 R13: 0000000000000046 R14: ffff88802c0ce300 R15: ffff88801ba4c7a8 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000003c80 CR3: 000000000cb30000 CR4: 00000000003506f0 Call Trace: lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline] lock_is_held_type+0x104/0x190 kernel/locking/lockdep.c:5826 lock_is_held include/linux/lockdep.h:288 [inline] advance_sched+0x161/0xc80 net/sched/sch_taprio.c:943 __run_hrtimer kernel/time/hrtimer.c:1750 [inline] __hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1814 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline] __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:119 [inline] RIP: 0010:lock_is_held_type+0x32/0x190 kernel/locking/lockdep.c:5818 Code: 56 41 55 41 54 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 bd ff ff ff ff 83 3d f0 db e2 03 00 0f 84 03 01 00 00 <65> 8b 05 df 0f 9b 75 85 c0 0f 85 f4 00 00 00 65 48 8b 1d a7 3b 9c RSP: 0018:ffffc90000107580 EFLAGS: 00000202 RAX: 19ee6f42aa0faf00 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff88801ba4bc00 RSI: 00000000ffffffff RDI: ffffffff8e084658 RBP: 00000000ffffffff R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000020ec0 R12: ffff88801c2f0e00 R13: 0000000000000000 R14: 0000000000000007 R15: ffffffff8e084658 lock_is_held include/linux/lockdep.h:288 [inline] neigh_flush_dev+0x198/0xa80 net/core/neighbour.c:394 __neigh_ifdown+0x3d/0x460 net/core/neighbour.c:447 neigh_ifdown+0x1f/0x30 net/core/neighbour.c:465 inetdev_destroy net/ipv4/devinet.c:332 [inline] inetdev_event+0x7e9/0x15c0 net/ipv4/devinet.c:1636 notifier_call_chain+0x197/0x390 kernel/notifier.c:93 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline] call_netdevice_notifiers net/core/dev.c:2078 [inline] unregister_netdevice_many_notify+0xf36/0x1810 net/core/dev.c:11086 ip6gre_exit_batch_net+0x449/0x490 net/ipv6/ip6_gre.c:1647 ops_exit_list net/core/net_namespace.c:178 [inline] cleanup_net+0x77f/0xb90 net/core/net_namespace.c:652 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 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 10330 jiffies! g10297 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:27752 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x99/0x380 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: CPU: 1 PID: 5931 Comm: kworker/1:4 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: events_power_efficient neigh_managed_work RIP: 0010:queued_write_lock_slowpath+0x125/0x294 kernel/locking/qrwlock.c:85 Code: f0 41 81 0e 00 01 00 00 42 0f b6 04 23 84 c0 74 37 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 2a 4c 89 f7 e8 bf be 6b f7 eb 20 f3 90 <42> 0f b6 04 23 84 c0 74 15 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 08 RSP: 0018:ffffc900044c79e0 EFLAGS: 00000206 RAX: 00000000000001ff RBX: 1ffffffff1c108c8 RCX: ffffffff8a713fab RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8e084640 RBP: ffffc900044c7a90 R08: ffffffff8e084643 R09: 1ffffffff1c108c8 R10: dffffc0000000000 R11: fffffbfff1c108c9 R12: dffffc0000000000 R13: 1ffff92000898f40 R14: ffffffff8e084640 R15: ffffc900044c7a30 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c007d63000 CR3: 00000000264b0000 CR4: 00000000003506e0 Call Trace: queued_write_lock include/asm-generic/qrwlock.h:101 [inline] do_raw_write_lock+0x1ee/0x260 kernel/locking/spinlock_debug.c:210 neigh_managed_work+0x34/0x240 net/core/neighbour.c:1618 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 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