rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=7169, q=155 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294958796-4294948294), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g7169 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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:27400 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4312 Comm: syz-executor416 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:rcu_read_lock_held_common kernel/rcu/update.c:112 [inline] RIP: 0010:rcu_read_lock_held+0x15/0x40 kernel/rcu/update.c:309 Code: 00 00 00 00 00 e8 9b 3b 01 00 e9 16 3f 01 00 66 0f 1f 44 00 00 53 e8 0a 5e a6 08 85 c0 74 26 31 db e8 ff 09 01 00 84 c0 74 20 56 0b 01 00 84 c0 74 17 48 c7 c7 20 b1 92 8c be ff ff ff ff 5b RSP: 0018:ffffc900001e0c20 EFLAGS: 00000002 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 04c603310b073300 RDX: ffff888079093b80 RSI: ffffffff8abef900 RDI: ffffffff8abef8c0 RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff2119049 R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: ffff888023836c58 R13: ffff88802e157b40 R14: ffff8880790941b8 R15: 0000000000000001 FS: 000055557e1283c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007faf9393d6c0 CR3: 0000000079b85000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: pid_task+0x9d/0x140 kernel/pid.c:401 send_sigqueue+0x137/0x600 kernel/signal.c:1978 posix_timer_event kernel/time/posix-timers.c:360 [inline] posix_timer_fn+0x16a/0x3d0 kernel/time/posix-timers.c:386 __run_hrtimer kernel/time/hrtimer.c:1747 [inline] __hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1811 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline] __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 Code: f5 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ae 05 49 f7 48 89 df e8 06 cb 49 f7 e8 d1 bd 6c f7 fb bf 01 00 00 00 96 43 3d f7 65 8b 05 27 f1 e7 75 85 c0 74 02 5b c3 e8 c4 02 e6 RSP: 0018:ffffc90003ef7b98 EFLAGS: 00000282 RAX: 04c603310b073300 RBX: ffff888078839bc0 RCX: 04c603310b073300 RDX: dffffc0000000000 RSI: ffffffff8a6c0600 RDI: 0000000000000001 RBP: ffff88807883a058 R08: dffffc0000000000 R09: ffffed100f107379 R10: ffffed100f107379 R11: 1ffff1100f107378 R12: 1ffff1100f10740b R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x1163/0x1350 kernel/signal.c:2874 arch_do_signal_or_restart+0xb7/0x1240 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7faf93924a4a Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 d3 69 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 33 6a 02 00 8b 44 24 RSP: 002b:00007ffd78e3c620 EFLAGS: 00000293 RAX: fffffffffffffff7 RBX: 0000000000000004 RCX: 00007faf93924a4a RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffd78e3c670 R09: 00007ffd78e3c670 R10: 0000000000000000 R11: 0000000000000293 R12: 00007faf939a8488 R13: 00007ffd78e3c65c R14: 0000000000000000 R15: 431bde82d7b634db INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.102 msecs