rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=1bc4/1/0x4000000000000000 softirq=18328/18334 fqs=1 rcu: (detected by 1, t=10502 jiffies, g=11537, q=3352 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 36 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x10/0xb0 kernel/rcu/tree.c:751 Code: 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 f0 22 fa 10 db 83 d3 09 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df RSP: 0018:ffffc90000007b20 EFLAGS: 00000083 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff99d5ac20 RBP: ffffffff84d040eb R08: 0000000000000001 R09: 0000000000000000 R10: ffffc90000007ca0 R11: fffff52000000f96 R12: 0000000000000000 R13: ffffffff99d5ac20 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888125c18000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcc19fd748 CR3: 000000000df36000 CR4: 00000000003526f0 Call Trace: trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0x5f/0x360 kernel/locking/lockdep.c:5831 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 debug_object_activate+0xbb/0x420 lib/debugobjects.c:818 debug_hrtimer_activate kernel/time/hrtimer.c:445 [inline] debug_activate kernel/time/hrtimer.c:484 [inline] enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1088 __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline] RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline] RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline] RIP: 0010:lock_release+0xa6/0x3e0 kernel/locking/lockdep.c:5885 Code: 25 08 80 a0 92 41 83 bf ec 0a 00 00 00 0f 85 1e 02 00 00 49 81 3e 20 43 64 93 0f 84 11 02 00 00 48 c7 44 24 20 00 00 00 00 9c <8f> 44 24 20 48 8b 5c 24 20 fa 48 c7 c7 36 bc 9c 8d e8 24 76 dc 09 RSP: 0018:ffffc90000ac6e68 EFLAGS: 00000202 RAX: 0000000000000000 RBX: ffffffff903fbc01 RCX: 34f5f870ee3b3300 RDX: ffffc90000ac6f01 RSI: ffffffff8be337e0 RDI: ffffffff8be337a0 RBP: dffffc0000000000 R08: ffffc90000ac7390 R09: 0000000000000000 R10: ffffc90000ac6ff8 R11: fffff52000158e01 R12: ffffc90000ac73a0 R13: ffffffff8172c195 R14: ffffffff8e139ee0 R15: ffff8881404d9e00 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:330 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:356 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4180 [inline] slab_alloc_node mm/slub.c:4229 [inline] kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4236 node_alloc net/ipv6/ip6_fib.c:188 [inline] fib6_add_1+0x9c1/0x1460 net/ipv6/ip6_fib.c:-1 fib6_add+0x204/0x18a0 net/ipv6/ip6_fib.c:1440 __ip6_ins_rt net/ipv6/route.c:1351 [inline] ip6_ins_rt+0xc8/0x120 net/ipv6/route.c:1361 __ipv6_ifa_notify+0x63f/0xac0 net/ipv6/addrconf.c:6283 ipv6_ifa_notify net/ipv6/addrconf.c:6322 [inline] addrconf_dad_completed+0x180/0xd60 net/ipv6/addrconf.c:4320 addrconf_dad_work+0xc36/0x14b0 net/ipv6/addrconf.c:-1 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies! g11537 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=3456 rcu: rcu_preempt kthread starved for 10500 jiffies! g11537 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245