INFO: rcu detected stall in futex

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-6.6	INFO: rcu detected stall in futex (2) origin:lts-only	1	C		inconclusive	26	1d01h	90d	0/2	upstream: reported C repro on 2025/10/31 01:02
upstream	INFO: rcu detected stall in sys_futex (7) kernel	1	syz	error		103	3d23h	584d	0/29	upstream: reported syz repro on 2024/06/24 16:48
linux-5.15	INFO: rcu detected stall in sys_futex (2) origin:lts-only	1	syz		error	58	3d12h	603d	0/3	upstream: reported syz repro on 2024/06/05 16:49
linux-6.6	INFO: rcu detected stall in futex origin:lts-only	1	C		done	6	154d	172d	2/2	fixed on 2025/10/06 10:09
linux-6.1	INFO: rcu detected stall in sys_futex origin:lts-only	1	syz		done	28	22d	939d	0/3	upstream: reported syz repro on 2023/07/05 11:35

rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10499 ticks this GP) idle=8ae/1/0x4000000000000000 softirq=14038/14038 fqs=0 (t=10500 jiffies g=13889 q=181) rcu: rcu_preempt kthread starved for 10500 jiffies! g13889 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:29176 pid: 13 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5064 schedule+0xcf/0x270 kernel/sched/core.c:5143 schedule_timeout+0x148/0x250 kernel/time/timer.c:1878 rcu_gp_fqs_loop kernel/rcu/tree.c:1940 [inline] rcu_gp_kthread+0xbbe/0x1d70 kernel/rcu/tree.c:2113 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 NMI backtrace for cpu 1 CPU: 1 PID: 10501 Comm: syz-executor.2 Not tainted 5.11.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x1f4/0x230 kernel/rcu/tree_stall.h:337 print_cpu_stall kernel/rcu/tree_stall.h:569 [inline] check_cpu_stall kernel/rcu/tree_stall.h:643 [inline] rcu_pending kernel/rcu/tree.c:3751 [inline] rcu_sched_clock_irq.cold+0x48e/0xedf kernel/rcu/tree.c:2580 update_process_times+0x16d/0x200 kernel/time/timer.c:1782 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1369 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1102 asm_call_irq_on_stack+0xf/0x20 </IRQ> __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xbd/0x100 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:kvm_wait arch/x86/kernel/kvm.c:860 [inline] RIP: 0010:kvm_wait+0x9c/0xd0 arch/x86/kernel/kvm.c:837 Code: 02 48 89 da 83 e2 07 38 d0 7f 04 84 c0 75 32 0f b6 03 41 38 c4 75 13 e8 c2 17 47 00 e9 07 00 00 00 0f 00 2d 36 31 17 08 fb f4 <e8> af 17 47 00 eb af c3 e9 07 00 00 00 0f 00 2d 20 31 17 08 f4 eb RSP: 0018:ffffc90002b2f9d0 EFLAGS: 00000202 RAX: 000000000000b07f RBX: ffffc90000e0a108 RCX: ffffffff81584977 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000246 R08: 0000000000000001 R09: ffffffff8ed31857 R10: fffffbfff1da630a R11: 0000000000000001 R12: 0000000000000003 R13: fffff520001c1421 R14: 0000000000000001 R15: ffff8880b9f35a00 pv_wait arch/x86/include/asm/paravirt.h:564 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x8b8/0xb40 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:113 spin_lock include/linux/spinlock.h:354 [inline] futex_wake+0x1b5/0x490 kernel/futex.c:1603 do_futex+0x322/0x1960 kernel/futex.c:3768 __do_sys_futex+0x2a2/0x470 kernel/futex.c:3826 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e219 Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fffe67ace78 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 000000000119bf8c RCX: 000000000045e219 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 000000000119bf88 RBP: 000000000119bf80 R08: 00000000011a0df8 R09: 0000000000000000 R10: 00007fffe67acf40 R11: 0000000000000246 R12: 0000000000000644 R13: 0000000000000000 R14: 0000000000000003 R15: 000000000119bf8c