rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=55585, q=37 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294984400-4294973898), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g55585 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:27736 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x99/0x3b0 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: 9966 Comm: syz.2.1662 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:__lock_acquire+0x1d4/0x7d10 kernel/locking/lockdep.c:4952 Code: 89 44 24 60 48 c7 c0 40 c1 bf 96 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85 72 65 00 00 83 3d 03 7b 5b 15 00 75 0b 83 7c 24 60 30 <0f> 83 fd 57 00 00 44 89 6c 24 34 4c 89 74 24 40 44 8b 6d 20 48 c7 RSP: 0018:ffffc90000007860 EFLAGS: 00000087 RAX: 0000000000000004 RBX: ffffffff8cb2d620 RCX: ffffffff96bfc103 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cb2d620 RBP: ffffc90000007ab0 R08: dffffc0000000000 R09: 0000000000000001 R10: dffffc0000000000 R11: fffffbfff1c3f9a6 R12: ffff8880259c1dc0 R13: 0000000000000000 R14: ffff8880259c2898 R15: ffffffff9047f200 FS: 00007f8cfda4c6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fa1fff8 CR3: 000000003ae85000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] __lock_task_sighand+0x42/0x2d0 kernel/signal.c:1394 lock_task_sighand include/linux/sched/signal.h:745 [inline] send_sigqueue+0x159/0x610 kernel/signal.c:1979 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+0x560/0xd70 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: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 9e 02 2e f7 48 89 df e8 e6 ca 2e f7 e8 31 1f 52 f7 fb bf 01 00 00 00 86 2b 22 f7 65 8b 05 47 b0 cb 75 85 c0 74 02 5b c3 e8 94 c4 c9 RSP: 0018:ffffc90014c77b98 EFLAGS: 00000282 RAX: c4e119806a074900 RBX: ffff8880793d9280 RCX: c4e119806a074900 RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: 0000000000000001 RBP: ffff8880793d9718 R08: ffff8880793d9283 R09: 1ffff1100f27b250 R10: dffffc0000000000 R11: ffffed100f27b251 R12: 1ffff1100f27b2e3 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+0xc4/0x1350 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:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f8cfcb9c629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8cfda4c028 EFLAGS: 00000246 RAX: 0000000000000021 RBX: 00007f8cfce15fa0 RCX: 00007f8cfcb9c629 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000000 RBP: 00007f8cfcc32b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8cfce16038 R14: 00007f8cfce15fa0 R15: 00007fff41540938