rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P17677/1:b..l P17681/1:b..l rcu: (detected by 0, t=10503 jiffies, g=142821, q=1490 ncpus=2) task:syz.3.3208 state:R running task stack:27528 pid:17681 tgid:17676 ppid:14738 task_flags:0x400040 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7277 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7599 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x910 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5947 Code: ff ff ff e8 50 15 42 0a f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 a2 c0 f1 11 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 bf 19 45 0a cc 48 8d 3d 97 47 da RSP: 0018:ffffc900036c7710 EFLAGS: 00000292 RAX: 1f685b412d89fc00 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 0000000010d5a36a RSI: ffffffff8e69bc48 RDI: ffffffff8c6da080 RBP: ffff88807bf18000 R08: ffffffff8241eb5e R09: 0000000000000000 R10: 000000000000000f R11: ffffffff81b28a90 R12: ffffffff8ed5c8e0 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:309 [inline] rcu_read_lock include/linux/rcupdate.h:849 [inline] __update_page_owner_free_handle+0x4b/0x4a0 mm/page_owner.c:301 __reset_page_owner+0x85/0x1f0 mm/page_owner.c:339 reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] __free_frozen_pages+0xc93/0xd90 mm/page_alloc.c:2962 __slab_free+0x274/0x2c0 mm/slub.c:5823 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_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_noprof+0x2b9/0x600 mm/slub.c:5010 lsm_file_alloc security/security.c:171 [inline] security_file_alloc+0x34/0x310 security/security.c:2406 init_file+0x90/0x2b0 fs/file_table.c:184 alloc_empty_file+0x74/0x1d0 fs/file_table.c:266 path_openat+0xa2/0x1d60 fs/namei.c:4986 do_file_open+0x23e/0x4a0 fs/namei.c:5029 do_sys_openat2+0x115/0x200 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd49155e98e RSP: 002b:00007fd48f38eea8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fd48f3916c0 RCX: 00007fd49155e98e RDX: 0000000000000002 RSI: 00007fd4916343da RDI: ffffffffffffff9c RBP: 00007fd49163503b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000036 R13: 0000200000000000 R14: 0000000000000000 R15: 00007fd49194fa48 task:syz.3.3208 state:R running task stack:25480 pid:17677 tgid:17676 ppid:14738 task_flags:0x400040 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7277 preempt_schedule_common+0x7f/0xd0 kernel/sched/core.c:7456 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __local_bh_enable_ip+0xe9/0x140 kernel/softirq.c:480 local_bh_enable include/linux/bottom_half.h:33 [inline] ipt_do_table+0x137f/0x15d0 net/ipv4/netfilter/ip_tables.c:357 nf_hook_entry_hookfn include/linux/netfilter.h:165 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook+0x22a/0x3a0 include/linux/netfilter.h:280 __ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120 ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129 ip_send_skb+0x45/0xc0 net/ipv4/ip_output.c:1511 udp_send_skb+0x7ed/0xf70 net/ipv4/udp.c:1174 udp_sendmsg+0x1971/0x2140 net/ipv4/udp.c:1456 sock_sendmsg_nosec+0x10e/0x180 net/socket.c:801 __sock_sendmsg net/socket.c:815 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2713 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767 __sys_sendmmsg+0x273/0x4d0 net/socket.c:2856 __do_sys_sendmmsg net/socket.c:2883 [inline] __se_sys_sendmmsg net/socket.c:2880 [inline] __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2880 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd49159e159 RSP: 002b:00007fd48f7f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007fd491825fa0 RCX: 00007fd49159e159 RDX: 000000000800001d RSI: 0000200000007fc0 RDI: 0000000000000003 RBP: 00007fd49163503b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000300 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd491826038 R14: 00007fd491825fa0 R15: 00007fd49194fa48 rcu: rcu_preempt kthread starved for 1989 jiffies! g142821 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:27488 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7277 __schedule_loop kernel/sched/core.c:7354 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7369 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 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: 14585 Comm: kworker/u8:23 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5947 Code: ff ff ff e8 50 15 42 0a f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 a2 c0 f1 11 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 bf 19 45 0a cc 48 8d 3d 97 47 da RSP: 0018:ffffc90000006a48 EFLAGS: 00000286 RAX: e7726e3445aae600 RBX: 0000000000000000 RCX: 8000000000000101 RDX: 000000004dbb4af1 RSI: ffffffff8e69bc48 RDI: ffffffff8c6da080 RBP: ffff8880322b3e80 R08: ffffffff8177f1df R09: 0000000000000000 R10: ffffc90000006b88 R11: fffff52000000d7d R12: ffffffff8ed5c8e0 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000246 FS: 0000000000000000(0000) GS:ffff888124cd1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000576000 CR3: 000000000eb48000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000009 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] rcu_read_lock include/linux/rcupdate.h:849 [inline] class_rcu_constructor include/linux/rcupdate.h:1216 [inline] unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495 __unwind_start+0x514/0x660 arch/x86/kernel/unwind_orc.c:787 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24 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 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6508 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6635 kfree_skb_reason include/linux/skbuff.h:1323 [inline] ip_rcv_finish_core+0x104e/0x1c00 net/ipv4/ip_input.c:469 ip_rcv_finish+0x14c/0x2a0 net/ipv4/ip_input.c:490 ip_sabotage_in+0x1e1/0x270 net/bridge/br_netfilter_hooks.c:988 nf_hook_entry_hookfn include/linux/netfilter.h:165 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:280 [inline] NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:323 __netif_receive_skb_one_core net/core/dev.c:6264 [inline] __netif_receive_skb net/core/dev.c:6377 [inline] netif_receive_skb_internal net/core/dev.c:6463 [inline] netif_receive_skb+0x45b/0xbf0 net/core/dev.c:6522 NF_HOOK+0xa4/0x3a0 include/linux/netfilter.h:325 br_handle_frame_finish+0x1136/0x1950 net/bridge/br_input.c:-1 br_nf_hook_thresh net/bridge/br_netfilter_hooks.c:1165 [inline] br_nf_pre_routing_finish+0x138a/0x1a10 net/bridge/br_netfilter_hooks.c:430 NF_HOOK+0x64e/0x6e0 include/linux/netfilter.h:325 br_nf_pre_routing+0xec2/0x14b0 net/bridge/br_netfilter_hooks.c:539 nf_hook_entry_hookfn include/linux/netfilter.h:165 [inline] nf_hook_bridge_pre net/bridge/br_input.c:291 [inline] br_handle_frame+0x1329/0x1600 net/bridge/br_input.c:451 __netif_receive_skb_core+0x989/0x30c0 net/core/dev.c:6151 __netif_receive_skb_one_core net/core/dev.c:6262 [inline] __netif_receive_skb net/core/dev.c:6377 [inline] process_backlog+0x727/0x18b0 net/core/dev.c:6728 __napi_poll+0xaa/0x330 net/core/dev.c:7787 napi_poll net/core/dev.c:7850 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:8007 handle_softirqs+0x226/0x860 kernel/softirq.c:645 do_softirq+0x77/0xd0 kernel/softirq.c:546 __local_bh_enable_ip+0x100/0x140 kernel/softirq.c:473 blake2s_compress+0xfa/0x1c00 lib/crypto/x86/blake2s.h:42 blake2s_final+0x10f/0x270 lib/crypto/blake2s.c:142 hmac+0x2dc/0x3b0 drivers/net/wireguard/noise.c:333 kdf+0x12d/0x290 drivers/net/wireguard/noise.c:367 mix_dh drivers/net/wireguard/noise.c:413 [inline] wg_noise_handshake_create_initiation+0x29e/0x810 drivers/net/wireguard/noise.c:550 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:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 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