rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P10911/2:b..l rcu: (detected by 1, t=10502 jiffies, g=43545, q=445 ncpus=2) task:syz-executor state:R running task stack:25752 pid:10911 tgid:10911 ppid:10903 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x169e/0x54f0 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:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5874 Code: ff ff ff e8 41 cc 95 09 f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 1b f7 d5 10 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 40 8f 99 09 cc 48 8d 3d b8 fb ef RSP: 0018:ffffc9000497f098 EFLAGS: 00000282 RAX: 7add9f8404e34e00 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 00000000ae223f6d RSI: ffffffff8d8b2d67 RDI: ffffffff8ba843e0 RBP: ffffffff81770226 R08: ffffffff81770226 R09: ffffffff8dfc8100 R10: ffffc9000497f1f8 R11: ffffffff81afc4e0 R12: 0000000000000002 R13: ffffffff8dfc8100 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xc3/0x2550 arch/x86/kernel/unwind_orc.c:495 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 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_mempool_unpoison_object+0xa3/0x130 mm/kasan/common.c:564 kasan_mempool_unpoison_object include/linux/kasan.h:391 [inline] napi_skb_cache_get+0x210/0x410 net/core/skbuff.c:306 __alloc_skb+0x19a/0x7d0 net/core/skbuff.c:696 alloc_skb include/linux/skbuff.h:1383 [inline] nlmsg_new include/net/netlink.h:1055 [inline] mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217 mpls_dev_sysctl_register+0x1dc/0x280 net/mpls/af_mpls.c:1453 mpls_add_dev net/mpls/af_mpls.c:1502 [inline] mpls_dev_notify+0x394/0xd10 net/mpls/af_mpls.c:1647 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2288 [inline] call_netdevice_notifiers net/core/dev.c:2302 [inline] register_netdevice+0x1751/0x1d10 net/core/dev.c:11509 __ip_tunnel_create+0x3e8/0x560 net/ipv4/ip_tunnel.c:268 ip_tunnel_init_net+0x2e7/0x840 net/ipv4/ip_tunnel.c:1147 vti_init_net+0x2f/0x100 net/ipv4/ip_vti.c:517 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137 setup_net+0x118/0x340 net/core/net_namespace.c:446 copy_net_ns+0x50e/0x730 net/core/net_namespace.c:579 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:132 unshare_nsproxy_namespaces+0x149/0x190 kernel/nsproxy.c:234 ksys_unshare+0x57d/0x9f0 kernel/fork.c:3244 __do_sys_unshare kernel/fork.c:3318 [inline] __se_sys_unshare kernel/fork.c:3316 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3316 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4f6fdedae7 RSP: 002b:00007ffd28ad3cf8 EFLAGS: 00000202 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f4f70065f40 RCX: 00007f4f6fdedae7 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000 RBP: 00007f4f700667b8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008 R13: 0000000000000003 R14: 00007ffd28ad3f38 R15: 0000000000000000 rcu: rcu_preempt kthread timer wakeup didn't happen for 10185 jiffies! g43545 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=29317 rcu: rcu_preempt kthread starved for 10186 jiffies! g43545 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:26856 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x169e/0x54f0 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+0x312/0x11b0 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 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: ab 59 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 03 3b 13 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: 00000246 RAX: 0000000000a8379f RBX: ffffffff81997c7a RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8d64fc83 RDI: ffffffff8ba843e0 RBP: ffffffff8dc07eb0 R08: ffff8880b8633e9b R09: 1ffff110170c67d3 R10: dffffc0000000000 R11: ffffed10170c67d4 R12: 0000000000000000 R13: 1ffffffff1b9fdd8 R14: 0000000000000000 R15: 1ffffffff1b9fdd8 FS: 0000000000000000(0000) GS:ffff888125eba000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000000000b CR3: 000000005ad7c000 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