rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P19260/1:b..l (detected by 0, t=10502 jiffies, g=119341, q=98) task:syz.3.3473 state:R running task stack:24624 pid:19260 ppid: 18524 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 preempt_schedule_notrace+0xd9/0x120 kernel/sched/core.c:6650 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 rcu_is_watching+0x72/0xa0 kernel/rcu/tree.c:1124 trace_lock_acquire include/trace/events/lock.h:13 [inline] lock_acquire+0xc8/0x400 kernel/locking/lockdep.c:5594 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] xfrm_policy_get_afinfo+0x2e/0x180 net/xfrm/xfrm_policy.c:241 xfrm_alloc_dst+0x15/0x150 net/xfrm/xfrm_policy.c:2496 xfrm_create_dummy_bundle net/xfrm/xfrm_policy.c:2926 [inline] xfrm_bundle_lookup net/xfrm/xfrm_policy.c:3018 [inline] xfrm_lookup_with_ifid+0xb9f/0x2000 net/xfrm/xfrm_policy.c:3126 xfrm_lookup net/xfrm/xfrm_policy.c:3223 [inline] xfrm_lookup_route+0x38/0x1a0 net/xfrm/xfrm_policy.c:3234 udp_sendmsg+0x15dd/0x2370 net/ipv4/udp.c:1245 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2499 __sys_sendmmsg+0x2ba/0x500 net/socket.c:2585 __do_sys_sendmmsg net/socket.c:2614 [inline] __se_sys_sendmmsg net/socket.c:2611 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2611 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f3c90ea3dd9 RSP: 002b:00007f3c8f0fd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f3c9111cfa0 RCX: 00007f3c90ea3dd9 RDX: 0000000000000300 RSI: 0000200000004d00 RDI: 0000000000000003 RBP: 00007f3c90f39d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000f1c R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3c9111d038 R14: 00007f3c9111cfa0 R15: 00007fffd2421aa8 rcu: rcu_preempt kthread timer wakeup didn't happen for 10233 jiffies! g119341 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=91168 rcu: rcu_preempt kthread starved for 10234 jiffies! g119341 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:27352 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3936 [inline] rcu_sched_clock_irq+0x843/0x1120 kernel/rcu/tree.c:2619 update_process_times+0x193/0x200 kernel/time/timer.c:2021 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4b4/0xb70 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:730 Code: b7 48 89 df e8 76 39 f8 f7 eb ad e8 4f af f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d 97 b5 5f 00 fb f4 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48 RSP: 0018:ffffffff8c007dc8 EFLAGS: 000002c6 RAX: 5d16878d55412d00 RBX: ffffffff8c0bc480 RCX: 5d16878d55412d00 RDX: 0000000000000001 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe00 RBP: ffffffff8c007ef8 R08: ffff8880b903b30b R09: 1ffff11017207661 R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffffffff1800fc4 R13: dffffc0000000000 R14: 1ffffffff1817890 R15: 0000000000000000 default_idle_call+0x81/0xc0 kernel/sched/idle.c:112 cpuidle_idle_call kernel/sched/idle.c:202 [inline] do_idle+0x3a1/0x650 kernel/sched/idle.c:326 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:424 start_kernel+0x489/0x540 init/main.c:1154 secondary_startup_64_no_verify+0xb1/0xbb