rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5651/1:b..l P19788/1:b..l P19121/1:b..l rcu: (detected by 1, t=10503 jiffies, g=216753, q=764 ncpus=2) task:syz.2.4009 state:R running task stack:26872 pid:19121 tgid:19121 ppid:5651 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x14f/0x760 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:5872 Code: ff ff ff e8 e1 11 07 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 cb 7c 97 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 58 61 92 RSP: 0018:ffffc90004a4f078 EFLAGS: 00000286 RAX: bdc5c2605b580900 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 00000000a69b4a9e RSI: ffffffff8e219b45 RDI: ffffffff8c28af60 RBP: ffffffff8176f256 R08: ffffffff8176f256 R09: ffffffff8e95cd60 R10: ffffc90004a4f1d8 R11: ffffffff81b0ebd0 R12: 0000000000000002 R13: ffffffff8e95cd60 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+0x3e/0x60 mm/kasan/common.c:57 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556 __call_rcu_common kernel/rcu/tree.c:3131 [inline] call_rcu+0xee/0x890 kernel/rcu/tree.c:3251 slab_free_hook mm/slub.c:2653 [inline] slab_free mm/slub.c:6250 [inline] kmem_cache_free+0x462/0x650 mm/slub.c:6377 anon_vma_free mm/rmap.c:137 [inline] __put_anon_vma+0x12b/0x2d0 mm/rmap.c:2915 put_anon_vma mm/internal.h:216 [inline] unlink_anon_vmas+0x58b/0x730 mm/rmap.c:536 free_pgtables+0x836/0xb70 mm/memory.c:414 exit_mmap+0x490/0x9e0 mm/mmap.c:1312 __mmput+0x118/0x430 kernel/fork.c:1178 exit_mm+0x18e/0x250 kernel/exit.c:581 do_exit+0x6a2/0x22c0 kernel/exit.c:963 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117 get_signal+0x1284/0x1330 kernel/signal.c:3037 arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe34875d60e RSP: 002b:00007fe3495a6f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: fffffffffffffdfc RBX: 00007fe3495a76c0 RCX: 00007fe34875d60e RDX: 00007fe3495a6fb0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fe348832d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe348a16038 R14: 00007fe348a15fa0 R15: 00007fe348b3fa48 task:syz.2.4183 state:R running task stack:26872 pid:19788 tgid:19788 ppid:5651 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7370 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:190 spin_unlock include/linux/spinlock.h:390 [inline] zap_pte_range mm/memory.c:1948 [inline] zap_pmd_range mm/memory.c:2004 [inline] zap_pud_range mm/memory.c:2032 [inline] zap_p4d_range mm/memory.c:2053 [inline] __zap_vma_range+0x3d17/0x4b40 mm/memory.c:2093 unmap_vmas+0x379/0x530 mm/memory.c:2162 exit_mmap+0x280/0x9e0 mm/mmap.c:1300 __mmput+0x118/0x430 kernel/fork.c:1178 exit_mm+0x18e/0x250 kernel/exit.c:581 do_exit+0x6a2/0x22c0 kernel/exit.c:963 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117 get_signal+0x1284/0x1330 kernel/signal.c:3037 arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe34875d60e RSP: 002b:00007fe3495a6f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: fffffffffffffdfc RBX: 00007fe3495a76c0 RCX: 00007fe34875d60e RDX: 00007fe3495a6fb0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fe348832d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe348a16038 R14: 00007fe348a15fa0 R15: 00007fe348b3fa48 task:syz-executor state:R running task stack:22056 pid:5651 tgid:5651 ppid:1 task_flags:0x40054c flags:0x00080003 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7370 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_read_unlock include/linux/rwlock_api_smp.h:256 [inline] _raw_read_unlock+0x3f/0x50 kernel/locking/spinlock.c:264 zap_pid_ns_processes+0x2c9/0x5f0 kernel/pid_namespace.c:233 find_child_reaper kernel/exit.c:623 [inline] forget_original_parent kernel/exit.c:707 [inline] exit_notify kernel/exit.c:744 [inline] do_exit+0x1f66/0x22c0 kernel/exit.c:987 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117 get_signal+0x1284/0x1330 kernel/signal.c:3037 arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe34875d60e RSP: 002b:00007fe348b3fd28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: 0000000000000000 RBX: 0000555563e91500 RCX: 00007fe34875d60e RDX: 00007fe348b3fd80 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fe348b3fdec R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000386 R13: 000000000000004f R14: 0000000000106c52 R15: 00007fe348b3fe40 rcu: rcu_preempt kthread starved for 4319 jiffies! g216753 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:26784 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0x164/0x360 kernel/sched/core.c:7283 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 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: 5865 Comm: kworker/u8:30 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker RIP: 0010:__lock_acquire+0x92/0x2cf0 kernel/locking/lockdep.c:5107 Code: 70 03 fd 93 41 0f 45 c8 89 4c 24 10 8b 0d 46 de a2 18 85 c9 0f 95 c0 83 fe 08 0f 92 c2 08 c2 0f 84 49 01 00 00 83 fe 01 77 0c <89> f0 49 8b 44 c1 08 48 85 c0 75 21 31 ed 4c 89 cf 31 d2 4c 89 cb RSP: 0018:ffffc90000006c70 EFLAGS: 00000097 RAX: ffffffff9a48bb00 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff8e95cd60 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8e95cd60 R10: ffffc90000006f78 R11: ffffffff81b0ebd0 R12: 0000000000000002 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88812528d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000003eb030 CR3: 000000007e468000 CR4: 00000000003526f0 DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 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 kasan_save_free_info+0x46/0x50 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:2689 [inline] slab_free mm/slub.c:6250 [inline] kfree+0x1c5/0x640 mm/slub.c:6565 skb_kfree_head net/core/skbuff.c:1075 [inline] skb_free_head net/core/skbuff.c:1087 [inline] skb_release_data+0x828/0xa60 net/core/skbuff.c:1114 skb_release_all net/core/skbuff.c:1189 [inline] __kfree_skb+0x5d/0x210 net/core/skbuff.c:1203 nft_synproxy_eval_v4+0x352/0x4e0 net/netfilter/nft_synproxy.c:61 nft_synproxy_do_eval+0x305/0x580 net/netfilter/nft_synproxy.c:142 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x48d/0x1ae0 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x360/0x4b0 net/netfilter/nft_chain_filter.c:162 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+0x21f/0x3c0 include/linux/netfilter.h:316 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6202 [inline] __netif_receive_skb net/core/dev.c:6315 [inline] process_backlog+0xaa3/0x1950 net/core/dev.c:6666 __napi_poll+0xae/0x340 net/core/dev.c:7730 napi_poll net/core/dev.c:7793 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7950 handle_softirqs+0x22a/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+0xf9/0x1eb0 lib/crypto/x86/blake2s.h:42 blake2s_final+0x116/0x260 lib/crypto/blake2s.c:142 hmac+0x20c/0x3b0 drivers/net/wireguard/noise.c:325 kdf+0x126/0x2b0 drivers/net/wireguard/noise.c:367 mix_precomputed_dh drivers/net/wireguard/noise.c:426 [inline] wg_noise_handshake_create_initiation+0x473/0x830 drivers/net/wireguard/noise.c:560 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:34 [inline] wg_packet_handshake_send_worker+0x18d/0x350 drivers/net/wireguard/send.c:51 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 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