rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=6b7c/1/0x4000000000000000 softirq=60647/60648 fqs=9 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P15684/1:b..l (detected by 0, t=10502 jiffies, g=89309, q=116 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 13913 Comm: kworker/1:2 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_power_efficient neigh_periodic_work RIP: 0010:mark_lock+0xec/0x320 kernel/locking/lockdep.c:-1 Code: 06 02 00 00 83 3d 83 65 5b 15 00 74 36 45 31 ff 49 83 c7 50 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 74 87 6e 00 01 00 00 00 45 85 27 74 50 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 RSP: 0018:ffffc90004937860 EFLAGS: 00000046 RAX: 1ffffffff2099a6a RBX: ffff88802a743c00 RCX: ffffffff8164fb84 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90aff2f8 RBP: 0000000000000002 R08: ffffffff90aff2ff R09: 1ffffffff215fe5f R10: dffffc0000000000 R11: fffffbfff215fe60 R12: 0000000000000004 R13: dffffc0000000000 R14: ffff88802a744708 R15: ffffffff904cd350 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005559b3d9b6d0 CR3: 000000000c88e000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: mark_held_locks kernel/locking/lockdep.c:4230 [inline] __trace_hardirqs_on_caller kernel/locking/lockdep.c:4248 [inline] lockdep_hardirqs_on_prepare+0x249/0x770 kernel/locking/lockdep.c:4315 trace_hardirqs_on+0x34/0x40 kernel/trace/trace_preemptirq.c:49 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728 RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685 Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 82 30 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08 RSP: 0018:ffffc90004937a20 EFLAGS: 00000206 RAX: d4d25c7fc6f57400 RBX: 1ffff92000926f4c RCX: d4d25c7fc6f57400 RDX: dffffc0000000000 RSI: ffffffff8a8c1aa0 RDI: ffffffff8adf2060 RBP: ffffc90004937b08 R08: ffffffff90aff27f R09: 1ffffffff215fe4f R10: dffffc0000000000 R11: fffffbfff215fe50 R12: 0000000000000246 R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426 rcu_read_unlock include/linux/rcupdate.h:823 [inline] __neigh_notify+0x2a4/0x300 net/core/neighbour.c:3538 neigh_cleanup_and_release+0xc6/0x2e0 net/core/neighbour.c:102 neigh_periodic_work+0x3f3/0xd70 net/core/neighbour.c:1010 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 task:udevd state:R running task stack:22960 pid:15684 ppid:3641 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874 irqentry_exit+0x63/0x70 kernel/entry/common.c:439 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x7e/0x80 kernel/kcov.c:315 Code: 8d 52 28 4d 39 ca 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 05 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 90 48 8b 04 24 65 48 8b 0d b4 ef 7f 7e 65 8b 15 b5 ef 7f 7e 81 RSP: 0018:ffffc90003e0f5a8 EFLAGS: 00000293 RAX: ffffffff818f1be7 RBX: 00007f6cb46f16c5 RCX: 0000000000000000 RDX: ffff8880492fbc00 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff215fe48 R10: dffffc0000000000 R11: fffffbfff215fe49 R12: ffff8880492fbc00 R13: ffffc90003e0fa60 R14: 00007f6cb46f16c5 R15: 1ffff920007c1ed2 rcu_read_lock include/linux/rcupdate.h:792 [inline] is_bpf_text_address+0x57/0x2a0 kernel/bpf/core.c:735 kernel_text_address+0x9c/0xd0 kernel/extable.c:125 __kernel_text_address+0x9/0x30 kernel/extable.c:79 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] kmem_cache_free+0xf7/0x290 mm/slub.c:3709 remove_vma mm/mmap.c:144 [inline] exit_mmap+0x4a0/0x960 mm/mmap.c:3272 __mmput+0x118/0x3c0 kernel/fork.c:1206 exit_mm+0x25a/0x360 kernel/exit.c:566 do_exit+0x905/0x2480 kernel/exit.c:868 do_group_exit+0x217/0x2d0 kernel/exit.c:1024 __do_sys_exit_group kernel/exit.c:1035 [inline] __se_sys_exit_group kernel/exit.c:1033 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1033 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f6cb46f16c5 RSP: 002b:00007ffe3cc5d7c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00005559b3d957d0 RCX: 00007f6cb46f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 00005559b3d74910 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe3cc5d810 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread timer wakeup didn't happen for 10483 jiffies! g89309 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=56765 rcu: rcu_preempt kthread starved for 10484 jiffies! g89309 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:27248 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 PID: 56 Comm: kworker/u4:4 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: netns cleanup_net RIP: 0010:queued_write_lock_slowpath+0x12f/0x26f kernel/locking/qrwlock.c:85 Code: 99 f7 f0 81 0b 00 01 00 00 43 0f b6 04 27 84 c0 74 35 89 d9 80 e1 07 80 c1 03 38 c1 7c 29 48 89 df e8 35 ef 99 f7 eb 1f f3 90 <43> 0f b6 04 27 84 c0 74 14 89 d9 80 e1 07 80 c1 03 38 c1 7c 08 48 RSP: 0018:ffffc900015773c0 EFLAGS: 00000206 RAX: 00000000000001ff RBX: ffffffff8de55da0 RCX: ffffffff8a3993e7 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8de55da0 RBP: ffffc90001577470 R08: ffffffff8de55da3 R09: 1ffffffff1bcabb4 R10: dffffc0000000000 R11: fffffbfff1bcabb5 R12: dffffc0000000000 R13: 1ffff920002aee7c R14: ffffc90001577410 R15: 1ffffffff1bcabb4 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc4f1ad59a0 CR3: 000000000c88e000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: queued_write_lock include/asm-generic/qrwlock.h:101 [inline] do_raw_write_lock+0x1e6/0x260 kernel/locking/spinlock_debug.c:210 __neigh_ifdown+0x2c/0x460 net/core/neighbour.c:446 neigh_ifdown+0x1b/0x30 net/core/neighbour.c:465 rt6_disable_ip+0x7a3/0x810 net/ipv6/route.c:4950 addrconf_ifdown+0x16e/0x1a50 net/ipv6/addrconf.c:3798 addrconf_notify+0x405/0xf40 net/ipv6/addrconf.c:-1 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline] call_netdevice_notifiers net/core/dev.c:2066 [inline] unregister_netdevice_many_notify+0x10ac/0x19c0 net/core/dev.c:11023 vti6_exit_batch_net+0x3d2/0x420 net/ipv6/ip6_vti.c:1191 ops_exit_list net/core/net_namespace.c:177 [inline] cleanup_net+0x791/0xba0 net/core/net_namespace.c:640 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295