rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=7533, q=80 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294955972-4294945470), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g7533 f0x2 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:27720 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4283 Comm: syz-executor383 Not tainted 6.1.140-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:check_wait_context kernel/locking/lockdep.c:4746 [inline] RIP: 0010:__lock_acquire+0x9b0/0x7c50 kernel/locking/lockdep.c:4999 Code: e8 03 42 0f b6 04 00 84 c0 0f 85 e6 00 00 00 41 0f b6 06 84 c0 74 0e 41 0f b6 cd 44 0f b6 e8 38 c1 44 0f 42 e9 48 8b 44 24 70 <42> 0f b6 04 00 84 c0 0f 85 e3 00 00 00 48 ff c3 48 8b 44 24 40 48 RSP: 0018:ffffc900000077c0 EFLAGS: 00000046 RAX: 1ffff11004facc83 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff908b8310 RBP: ffffc90000007a10 R08: dffffc0000000000 R09: fffffbfff2117063 R10: fffffbfff2117063 R11: 1ffffffff2117062 R12: ffff888027d66440 R13: 0000000000000002 R14: ffffffff9028ef38 R15: ffff888027d66440 FS: 000055555cb193c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000006b000 CR3: 0000000018ac5000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 __lock_task_sighand+0x146/0x2d0 kernel/signal.c:1411 lock_task_sighand include/linux/sched/signal.h:745 [inline] send_sigqueue+0x159/0x600 kernel/signal.c:1979 posix_timer_event kernel/time/posix-timers.c:359 [inline] posix_timer_fn+0x16a/0x3d0 kernel/time/posix-timers.c:385 __run_hrtimer kernel/time/hrtimer.c:1691 [inline] __hrtimer_run_queues+0x522/0xc80 kernel/time/hrtimer.c:1755 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1817 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 ce 2e 4a f7 48 89 df e8 26 f4 4a f7 e8 91 f6 6d f7 fb bf 01 00 00 00 36 71 3e f7 65 8b 05 d7 32 e9 75 85 c0 74 02 5b c3 e8 24 44 e7 RSP: 0018:ffffc90003dd7bb8 EFLAGS: 00000286 RAX: 2eabe683a27ad200 RBX: ffff88802f7dca00 RCX: 2eabe683a27ad200 RDX: dffffc0000000000 RSI: ffffffff8a6c0000 RDI: 0000000000000001 RBP: ffff88802f7dce98 R08: dffffc0000000000 R09: ffffed1005efb941 R10: ffffed1005efb941 R11: 1ffff11005efb940 R12: 1ffff11005efb9d3 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+0xb0/0x1230 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xb1/0x140 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: 0033:0x7fb41849d899 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 19 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdc2288f78 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fb41849d899 RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007fb41845d990 R09: 00007fb41845d990 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb4184fb33c R13: 00007fb4184f5106 R14: 00007ffdc2288fb0 R15: 0000000000000000 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.425 msecs