rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P22088/1:b..l rcu: (detected by 0, t=10504 jiffies, g=109469, q=1146 ncpus=2) task:syz.0.3977 state:R running task stack:23728 pid:22088 tgid:22087 ppid:19012 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872 Code: ff ff ff e8 81 80 11 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 6b 7b 9d 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 90 80 14 0a cc 48 8d 3d b8 3b 94 RSP: 0018:ffffc90003ad62e0 EFLAGS: 00000282 RAX: 355efddee56f7600 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 00000000ffc3cb49 RSI: ffffffff8e25a5ad RDI: ffffffff8c2a9f80 RBP: ffffffff8176f21f R08: ffffffff8176f21f R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8e959c20 R12: 0000000000000002 R13: ffffffff8e959c20 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xac/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 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950 __slab_free+0x274/0x2c0 mm/slub.c:5767 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_kmalloc+0x22/0xb0 mm/kasan/common.c:406 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5362 [inline] __kmalloc_node_track_caller_noprof+0x4c3/0x730 mm/slub.c:5497 __kmemdup_nul mm/util.c:64 [inline] kstrdup+0x42/0x100 mm/util.c:84 __kernfs_new_node+0xa9/0x980 fs/kernfs/dir.c:661 kernfs_new_node+0xea/0x140 fs/kernfs/dir.c:751 kernfs_create_link+0xa7/0x200 fs/kernfs/symlink.c:39 sysfs_do_create_link_sd+0x83/0x110 fs/sysfs/symlink.c:44 device_add_class_symlinks+0x1cf/0x240 drivers/base/core.c:3516 device_add+0x467/0xb80 drivers/base/core.c:3708 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2337 register_netdevice+0x1433/0x1eb0 net/core/dev.c:11440 __vxlan_dev_create+0xd6/0x5e0 drivers/net/vxlan/vxlan_core.c:3977 vxlan_newlink+0x1a6/0x230 drivers/net/vxlan/vxlan_core.c:4410 rtnl_newlink_create+0x310/0xb00 net/core/rtnetlink.c:3913 __rtnl_newlink net/core/rtnetlink.c:4044 [inline] rtnl_newlink+0x167f/0x1bd0 net/core/rtnetlink.c:4159 rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7076 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775 __sock_sendmsg net/socket.c:790 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2684 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738 __sys_sendmsg net/socket.c:2770 [inline] __do_sys_sendmsg net/socket.c:2775 [inline] __se_sys_sendmsg net/socket.c:2773 [inline] __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f367ed9de59 RSP: 002b:00007f367fd29028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f367f025fa0 RCX: 00007f367ed9de59 RDX: 0000000004000084 RSI: 0000200000000000 RDI: 0000000000000003 RBP: 00007f367ee33e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f367f026038 R14: 00007f367f025fa0 R15: 00007ffc9eac52c8 rcu: rcu_preempt kthread starved for 1599 jiffies! g109469 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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 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: CPU: 0 UID: 0 PID: 8072 Comm: kworker/u8:20 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872 Code: ff ff ff e8 81 80 11 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 6b 7b 9d 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 90 80 14 0a cc 48 8d 3d b8 3b 94 RSP: 0018:ffffc90000006c80 EFLAGS: 00000282 RAX: 828cb38ab240f600 RBX: 0000000000000000 RCX: 0000000080000101 RDX: 00000000a42637f2 RSI: ffffffff8e25a5ad RDI: ffffffff8c2a9f80 RBP: ffffffff8176f21f R08: ffffffff8176f21f R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8e959c20 R12: 0000000000000002 R13: ffffffff8e959c20 R14: 0000000000000000 R15: 0000000000000246 FS: 0000000000000000(0000) GS:ffff888125226000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000563b1a7920f0 CR3: 00000000776f2000 CR4: 00000000003526f0 Call Trace: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xac/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_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4612 [inline] slab_alloc_node mm/slub.c:4945 [inline] kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959 skb_ext_maybe_cow net/core/skbuff.c:7112 [inline] skb_ext_add+0x1b6/0x8e0 net/core/skbuff.c:7187 nf_bridge_unshare net/bridge/br_netfilter_hooks.c:170 [inline] br_nf_forward_ip+0xc3/0xa30 net/bridge/br_netfilter_hooks.c:686 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x23e/0x3f0 include/linux/netfilter.h:316 __br_forward+0x397/0x540 net/bridge/br_forward.c:115 br_handle_frame_finish+0x1175/0x1990 net/bridge/br_input.c:229 br_nf_hook_thresh+0x3dd/0x4c0 net/bridge/br_netfilter_hooks.c:-1 br_nf_pre_routing_finish_ipv6+0x90c/0xc40 net/bridge/br_netfilter_ipv6.c:-1 NF_HOOK include/linux/netfilter.h:318 [inline] br_nf_pre_routing_ipv6+0x382/0x6f0 net/bridge/br_netfilter_ipv6.c:183 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_bridge_pre net/bridge/br_input.c:291 [inline] br_handle_frame+0x127f/0x1510 net/bridge/br_input.c:442 __netif_receive_skb_core+0x989/0x30b0 net/core/dev.c:6093 __netif_receive_skb_one_core net/core/dev.c:6204 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0x706/0x1860 net/core/dev.c:6670 __napi_poll+0xaa/0x330 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7949 handle_softirqs+0x225/0x840 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 blake2s_compress+0xfa/0x1c00 lib/crypto/x86/blake2s.h:42 blake2s_update+0x140/0x450 lib/crypto/blake2s.c:119 hmac+0x1f4/0x3b0 drivers/net/wireguard/noise.c:324 kdf drivers/net/wireguard/noise.c:360 [inline] message_ephemeral+0x233/0x310 drivers/net/wireguard/noise.c:493 wg_noise_handshake_create_initiation+0x24f/0x810 drivers/net/wireguard/noise.c:545 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:34 [inline] wg_packet_handshake_send_worker+0x18c/0x370 drivers/net/wireguard/send.c:51 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486 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